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COPYRIGHT DEPOSm 



THE FARMER'S PRACTICAL LIBRARY 

EDITED BY ERNEST INGERSOLL 



ROADS, PATHS AND BRIDGES 

BY 

LOGAN WALLER PAGE 



TLe Farmers Practical 
Library 

EDITED BY ERNEST INGERSOLL 

Cloth i6mo Illustrated 

From Kitchen to Garret. By Virginia 
Terhune Van de Water. 

Neighborhood Entertainments. By Renee 
B. Stern, of the Congressional Library. 

Home Waterworks. By Carleton J. 
Lynde, Professor of Physics in Mac- 
donald College, Quebec. 

Animal Competitors. By Ernest Ingersoll. 

Health on the Farm. By Dr. H. F. 

Harris, Secretary Georgia State Board 
of Health. 

Co-operation Among Farmers. By John 
Lee Coulter. 

Roads, Paths and Bridges. By L. W. 

Page, Chief of the Office of Public 
Roads, U. S. Department of Agriculture. 

The Satisfactions of Country Life. By 
Dr. James W. Robertson, Principal of 
Macdonald College, Quebec. 

Farm Management. By C. W. Pugsley, 
Professor of Agronomy and Farm Man- 
agement in the University of Nebraska. 

Electricity on the Farm. By Frederick 
M. Conlee. 

The Farm Mechanic. By L. W. Chase, 
Professor of Farm Mechanics in the 
University of Nebraska. 

Ballads of the Countryside. By George 
S. Bryan. 



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A GRAVEL ROAD NEAR SAVANNAH, GA. 



ROADS, PATHS AND 
BRIDGES 



BY 

LOGAN WALLER PAGE 

DIRECTOR, UNITED STATES OFFICE OP PUBLIC ROADS; 
PRESIDENT, AMERICAN ASSOCIATION FOR HIGHWAY IMPROVEMENT; 

AND 
MEMBER, AMERICAN SOCIETY OF CIVIL ENGINEERS 



ILLUSTRATED 



IRew l^orfi 

STURGIS & WALTON 

COMPANY 

191^ 

All rights reserved 



ji 

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Copyright 1912 
By STURGIS & WALTON COMPANY 



Set up and electrotyped. Published June, 1912 



gcu3i9ioa .tV 



So 



INTEODUCTION 

BY THE GENERAL EDITOE 

This is the day of the small book. There is 
much to be done. Time is short. Information 
is earnestly desired, but it is wanted in compact 
form, confined directly to the subject in view, 
authenticated by real knowledge, and, withal, 
gracefully delivered. It is to fulfill these con- 
ditions that the present series has been pro- 
jected — to lend real assistance to those who are 
looking about for new tools and fresh ideas. 

It is addressed especially to the man and 
woman at a distance from the libraries, exhibi- 
tions, and daily notes of progress, which are 
the main advantage, to a studious mind, of liv- 
ing in or near a large city. The editor has had 
in view, especially, the farmer and villager 
who is striving to make the life of himself and 
his family broader and brighter, as well as to 
increase his bank account; and it is therefore 
in the humane, rather than in a commercial di- 
rection, that the Library has been planned. 



yi INTRODUCTION 

The average American little needs advice on 
tlie conduct of his farm or business; or, if lie 
thinks he does, a large supply of such help in 
farming and trading as books and periodicals 
can give, is available to him. But many a man 
who is well to do and knows how to continue 
to make money, is ignorant how to spend it in 
a way to bring to himself, and confer upon his 
wife and children, those conveniences, comforts 
and niceties which alone make money worth 
acquiring and life worth living. He hardly 
realizes that they are within his reach. 

For suggestion and guidance in this direction 
there is a real call, to which this series is an 
answer. It proposes to tell its readers how 
they can make work easier, health more secure, 
and the home more enjoyable and tenacious 
of the whole family. No evil in American rural 
life is so great as the tendency of the young 
people to leave the farm and the village. The 
only way to overcome this evil is to make rural 
life less hard and sordid ; more comfortable and 
attractive. It is to the solving of that problem 
that these books are addressed. Their central 
idea is to show how country life may be made 



INTRODUCTION vii 

richer in interest, broader in its activities and 
its outlook, and sweeter to the taste. 

To this end men and women who have given 
each a lifetime of study and thought to his or 
her speciality, will contribute to the Library, 
and it is safe to promise that each volume will 
join with its eminently practical information a 
still more valuable stimulation of thought. 

Eenest Ingeksoll. 



INTEODUCTION 

EoAD building is an art based upon a science. 
In the location and survey of roads, tbe prepa- 
ration of plans and estimates, and tbe selection 
of materials, the science of engineering plays 
an important part. A reasonably adequate 
working knowledge of the art of road building, 
however, may be acquired by the layman 
through careful attention to the fundamental 
principles underlying the building of roads and 
the methods which have proved sound in prac- 
tice. For instance, proper drainage will con- 
vert an impassable quagmire into a reasonably 
firm earth road, and a judicious mixing of sand 
and clay will utilise the good qualities and neu- 
tralise the bad qualities of each. 

Bridge construction is much more exclusively 
within the province of the engineer than is road 
construction, and it is wise economy to incur 
the expense necessary to secure engineering 
skill in both road and bridge building. There 



INTEODUCTION 

are times, however, when the farmer finds it 
necessary to depend upon his own resources in 
the building of small bridges, culverts and 
drains. In such cases a practical knowledge of 
the simplest theory and practice will often en- 
able him to obtain satisfactory results. 

It is the purpose of this book to give in a 
concise and elementary form the fundamental 
principles governing the construction of roads, 
paths and bridges for farm and neighbourhood 
purposes, and to set forth the details of con- 
struction and maintenance so that they may be 
followed without great difficulty. 

A knowledge of the origin and development 
of road building and the progress of road legis- 
lation and administration is not only of interest 
to the student, but is of real value to every citi- 
zen, as it enables him to consider intelligently 
proposed reforms in road laws and existing 
systems of administration. The opening chap- 
ters deal with this phase of the subject and, in 
addition, point out a few of the economic aspects 
of the road question. 



CONTENTS 

CHAPTER PAGE 

I HiSTOEY OF Road Building 3 

II Road Legislation and Administration ... 38 

III Locations, Surveys, Plans, Specifications . . 62 

IV The Earth Road 79 

V The Sand-Clay Road Ill 

VI The Gravel Road 124 

VII The Broken Stone Road 134 

VIII The Selection of Materials for Macadam Roads 163 

IX Maintenance and Repair 177 

The Earth Road— The Sand-Clay Road— The Gravel 
Road — The Macadam Road. 

X Roadside Treatment 207 

XI Modern Road Problems 215 

XII Paths 229 

XIII Culverts and Bridges 241 



ILLUSTRATIONS 

A Gravel Road near Savannah, Ga Frontispiece 

FACING PAGE 

Some Ancient^ Highways 5 

Simplon Pass, Switzerland, Pont Napoleon 12 

A Paved Street in Pompeii 12 

Holland's Highways 21 

Thomas Telford 28 

John L. McAdam 28 

Primitive Methods of Transportation 44 

A Toll-house on the National Road 44 

Destroyers of Property 49 

Economics of Good-Roads Building 53 

The Roads and the Schools 60 

Examples of Good and Bad Road Location in a Hilly 

Region 64 

Transformation of an Earth Road 85 

An Earth Road with Proper Crown 92 

An Undrained Prairie Road in Spring ...... 92 

■Road Machines Hauled by a Traction Engine . . . .101 

The Sand-clay Road 108 

Three Sorts of Good Roads 129 

Constructins: a Macadam Road 133 



ILLUSTRATIONS 

FACING PAGE 

Bad Road-construction 140 " 

Eoad-making Machinery 144 

Effect of Treatment with a Split-log Drag 181 ' 

Good and Bad Maintenance 188 

Specimen Eoads 209 ' 

The Automobile and the Road 224 ^ 

Path of Stone-screenings Beside an Oiled Macadam Road . 230 ' 

Concrete Culverts and Bridges 244 * 



EOADS, PATHS AND BRIDGES 



ROADS, PATHS AND BRIDGES 

CHAPTER I 
HISTORY OF ROAD BUILDING 

Savage man built no roads. His wants were 
few and of an individual character. When 
hunger dictated, he sought food in the forests, 
or in the streams and lakes, and soon came to 
know the regions where game and fish were 
most abundant. As time went on he came to 
know the best and most direct route to his 
sources of supply, and established for himself 
definite trails. As he began slowly to mount 
the ladder of civilisation his habitation became 
fixed, and communication with his own and 
other tribes led him to establish more definite 
routes of travel. Gradually his trails were 
widened so as to admit the passage of beasts of 
burden. These widened trails were no doubt 
our first primitive roads. 

At a mucli later stage in human development 

3 



4 EOADS, PATHS AND BEIDGES 

came the wheeled vehicle, and the war chariot 
was no doubt the precursor of the modern 
wagon. In history we find the chariot men- 
tioned as early as war itself. The Bible tells of 
the pursuit of the fleeing Israelites by Pharaoh 
with 600 picked chariots and a host of others- 
It is evident from this early general use of the 
chariot that roads, even in a somewhat modern 
sense, must have been a necessity at a very early 
period in our civilisation. The earliest authen- 
tic record which we have of stone-surfaced 
roads is found in Egypt. A little to the east 
of the Great Pyramids of Ghizeh have been dis- 
covered the remains of a great causeway, more 
than a mile in length. This is supposed to be 
a portion of the Great Highway built by King 
Cheops for the purpose of affording a passage 
across the sands for the transportation of the 
stone used in the construction of the Great 
Pyramids. This is no doubt the road on which 
Herodotus tells us that the Great King em- 
ployed 100,000 men for a period of ten years. 
It was built of massive stone blocks, which in 
places were ten feet thick, and was lined on 







SOiViE A^jCiEiS'T H1GHVVAV8. 

• 1. (Top.) Appian Way and ruins of the Claudian Aqueduct. 
2. Tombs along the Appian Way. 3. Avenue of Sphinxes at Kar- 
nak, Egypt. 



HISTORY OF ROAD BUILDING 5 

either side with mausoleums, temples, parks 
and statues. 

Ancient Imperial Highways, — Egypt is not 
the only land possessing relics of early road 
building. Babylon, the city of hanging gardens 
and great walls, at a very early date developed 
a high state of civilisation, and Semiramis, its 
great queen, was an enthusiastic road builder. 
It is at this period that we find what is prob- 
ably the first use of stone in bridge building, 
as the two portions of the city were joined by 
a stone bridge across the Euphrates. Strabo 
tells us that this wonderful bridge was built 
of large stone blocks, joined with plates of 
lead. At this period, more than 2,000 years 
before Christ, asphalt was used instead of 
mortar in constructing the vast walls around 
the city. Commerce flourished and great high- 
ways radiated to all the principal cities of the 
then known world. The highways leading to 
Susa, Ecbatana and Sardis, are especially men- 
tioned as being lined with travellers and beasts 
of burden transporting the wealth of commerce. 
It is said that a highway 400 miles long, and 



6 EOADS, PATHS AND BEIDGES 

paved with brick set in a mortar of asphaltum, 
connected Ninevah and Babylon. 

The conquering Persians probably learned 
the art of road building from the Babylonians, 
and instituted a system of military roads 
throughout their Empire. The Persians estab- 
lished a military messenger or post service, and 
at intervals of from 18 to 25 miles stations 
were established at which riders, whose swift- 
ness Herodotus informs us nothing mortal 
surpassed, secured fresh mounts. Their speed 
was estimated at from 60 to 120 miles per day. 
Strabo states that there were two branches of 
the great road leading from Babylon to Syria, 
on one of which only a moderate toll was ex- 
acted, and it was, therefore, much more fre- 
quented by travellers than the other branch. 
This is probably the earliest record of the col- 
lection of tolls. 

As to the details of the construction of these 
early roads and the system of maintenance in 
effect, we can judge only by inference; but, as 
practically all great works of the ancients of 
which we have definite knowledge were con- 
structed by forced labour, we must assume that 



HISTORY OF ROAD BUILDING 7 

their roads and bridges were built and main- 
tained in the same way. 

During the time of Solomon two routes from 
Palestine to Egypt are mentioned as being 
thronged with travellers, and while no direct 
mention can be found, several historians in- 
form us that the streets of Jerusalem were 
paved at least in part during this period. It 
is plain that exceptionally good roads must 
have existed to carry on the great commercial 
trade of the city and to transport the material 
required for the splendid temple of Solomon. 

The ancient Greeks were by no means igno- 
rant of road construction, if we are to judge 
from the attention bestowed on the subject by 
the senate of Athens and the governments of 
Thebes and Lacedaemon. The physical require- 
ments of Greece, however, were such as to call 
for but few roads. Paved highways are known 
to have led from Athens to the Piraeus and to 
the sacred shrine at Eleusis. In the ancient 
city of Thebes the office of telearch, or cleaner 
of streets, was the lowest office in existence. 
The ungrateful inhabitants, in order to show 
their contempt for Epaminondas because of his 



8 EOADS, PATHS AND BEIDGES 

failure to capture Corinth, elected him to the 
despised place. But this citizen, whom Cicero 
declared to have been the greatest man of all 
times and all nations, held that no man is above 
the service he can render to the public, and 
soon through his own efforts Epaminondas 
raised the office of telearch to be one of the most 
distinguished favours the people of Thebes 
could bestow. Later, Thucydides informs us 
that Archelaus did more for Macedonia than all 
his predecessors combined, because he pro- 
moted the development of the land by making 
roads, and thus contributed largely to making 
the interior more accessible. 

It was left to the Carthaginians to become 
instructors to the world in the art of road build- 
ing. Carthage is given the credit of having 
demonstrated to the world the strategic and 
economic value of improved roads. But for a 
splendid system of highways, which permitted 
an easy means of communication with all parts 
of her domains, she never could have reached 
the heights attained, either in commerce or war. 
The ready exchange of commerce by land as 
well as by sea made her able to withstand the 



HISTORY OF ROAD BUILDING 9 

terrible drains of long and bloody wars. In 
spite of the opposition of Athens and all the 
onslaughts of imperial Rome, and even in spite 
of the solemn edict, '^Carthago delenda est/* 
Carthage continued to stand as an ever-ready 
menace to Roman supremacy. But the Ro- 
mans were apt pupils. Ere long they saw at 
least the military advantage of roads upon 
which armies and supplies could be moved with 
celerity — a means, as it were, of increasing the 
reach of their swords. 

There is considerable doubt whether either the 
Romans or the Carthaginians realised to any large 
extent the commercial value of their roads. Both 
built them more as necessary adjuncts to the success- 
ful operations of war, offensive as well as defensive, 
than as avenues for commerce. Good roads were, in 
fact, the price of existence. They were absolutely 
necessary for the rapid movement of troops, as well aa 
for providing supplies for large armies. Commerce 
and exchange followed as a natural result. 

We know but little about the Carthaginians as road 
builders. In so far as they are concerned their art 
is lost. About the ancient ruins of Carthage are 
found to-day a few traces of a double road leading 
to Tunis and occasional traces of a road leading to- 
ward Camarat. These and a few ruins are the only 
visible remains of ancient Carthage, for, in spite of 



10 EOADS, PATHS AND BEIDGES 

the genius of her commanders, her natural develop- 
ment and great resources, Carthage was unable to 
withstand the continued onslaughts of her great rival. 
At last, after nearly 400 years of resistance, offensive 
as well as defensive, Carthage fell about 146 B. C, 
and imperial Rome began her mastery of the world. 



The Romans as Road Builders, — The Ro- 
mans are the first systematic road bnilders 
of whom we have definite knowledge. The 
first of their great roads, from Rome to Capna, 
a distance of 142 Italian miles, was begun by 
Appius Clandius, about 312 B. C, and is known 
as the Appian Way, or ^^The Queen of Roads." 
This avenue was later extended to Brundisium 
(Brindisi), or a total of 360 miles, and was 
probably completed by Julius C^sar. About 
220 B. C. the Flaminian Way was built. This 
is of special interest because of a stone-arch 
bridge across the river Nar, 60 miles from 
Rome. The central arch had a span of 150 
feet and a rise of 100 feet, and was pronounced 
by Addison as the stateliest ruin in Italy. 
After the completion of the Flaminian Way, 
road building progressed very rapidly, so that 
when Rome reached the height of her glory no 



HISTORY OF ROAD BUILDING 11 

less than 29 great military roads radiated from 
her gates. As has already been pointed out, 
these roads, like those of the Carthaginians, 
were built largely, if not entirely, for military 
purposes. They represented the visible ef- 
forts which the nation by and through her rul- 
ers made for her preservation and the exten- 
sion of her conquests. 

The Roman roads were, as a rule, laid out in 
approximately straight lines. Mountains, hills 
and valleys were crossed almost without any 
regard to topography. Hills were cut through 
and deep ravines filled in. Although these 
roads remain to some extent even to-day as 
splendid monuments of their builder's art (the 
Appian "Way is said to have been in good repair 
800 years after it was built), we can hardly 
credit these people with having intentionally 
built for the ages. More than likely the pon- 
derous construction they adopted was that 
which they, to the best of their ability, believed 
necessary for a reasonably permanent and sat- 
isfactory road. 

The extent of the Roman road system is 
astounding. Every conquered province was 



12 EOADS, PATHS AND BRIDGES 

soon traversed in all directions with connect- 
ing roads. Of the narrow paths, three to six 
feet wide, found in conquered Gaul, no less 
than 13,000 miles are said to have been im- 
proved. In Britain, the road improvement is 
estimated to have been at least 2,500 miles. 
Across the Alps, through Gaul to Spain, Aus- 
tria and the regions of the Danube, led the 
great military roads. Nor were the countries 
beyond the seas ignored. Straight to the 
water's edge led the road from Rome, and then 
on the shore beyond was the continuation. 
England, Sicily, Africa, and even Asia, all bear 
witness of the wonderful energy which strove 
to bind firmly every member of the great em- 
pire into a living whole. 

Nor was this energy directed exclusively 
toward imperial progress and the building of 
roads for the movement of legions, or to satiate 
an empire with the luxuries of remote countries. 
If not at first, at least later in her development, 
Rome saw in her roads value other than mili- 
tary, for in the reign of Augustus we find a 
seemingly well-devised system of crossroads 
leading to and connecting villages and even 




STMPLON PASS, SWITZERLAND. POXT NAPOLEON. 




A PAVED STREET IN POMPEII. 



HISTORY OF ROAD BUILDING 13 

farms with tlie great military roads. The 
roads were no longer exclusively military, but 
were also filling the domestic needs of the 
farmers. 

The construction proper of the best type con- 
sisted of four courses. The statumen or foun- 
dation was composed of large flat stones bedded 
in mortar. On this foundation was placed a 
layer of hand rock laid in lime or cement mor- 
tar, known as the rudus. The nucleus consisted 
of small stones, gravel, or pieces of brick and 
broken tile, laid in mortar. On top of this was 
placed the summa crusta, or wearing surface, 
of large, flat, closely bedded rocks, making the 
total depth of the road about three feet. Un- 
der present conditions and prices of labour, , 
even aided by all our modern machinery, such \ 
roads would probably cost from $50,000 to 
$200,000 per mile, and though the Roman roads 
were built in part by slave labour and the spoils 
of war, they represent an enormous outlay. 

The Roman roads, though solid enough to 
bear the heaviest loads and durable beyond 
question, still lacked many of the essentials of 
a good road. The steep grades and their ex- 



14 EOADS, PATHS AND BEIDGES 

cessive hardness made them very wearisome to 
travellers, and Horace informs ns that ^^they; 
were less fatiguing to those who travelled 
slowly. ' ' Even on these roads, which we would 
think nothing could injure, we find that the 
weight and nature of the traffic were closely 
regulated by statutes which were rigidly en- 
forced. 

The highway legislation of the Eomans forms the 
basis for our present road laws. By the Roman law, 
the use of the roads was for the public. The roads 
could be the property of no individual, while the 
emperors or other chief magistrates were their con- 
servators. The majority of the main highways were 
built by contract at the public expense. Their main- 
tenance was in part by the labour of soldiers, convicts 
or slaves, or by an enforced service which, in some 
instances, took the form of taxation. In whatever form 
the maintenance was made, it was at the expense of 
the district through which the road passed. Tolls as 
a means of repairing highways appear to have been 
seldom resorted to. Some of the Roman roads were 
constructed through the private munificence of her 
emperors or other great personages ambitious of 
popularity, or with the spoils of war brought home 
by successful generals. The supervision of the roads 
was entrusted to men of the highest rank. Augustus 
himself seems to have made those about Rome his 
special care. The crossroads or vicinal roads were 



HISTORY OF ROAD BUILDING 15 

committed to the charge of the local magistrates, and, 
as a rule, maintained by compulsory labour, or the 
contributions of the whole neighbourhood, although 
occasionally a portion of a road was assigned to some 
landowner to maintain at his own cost. 

Roads in 'Ancient Peru and Mexico, — The 
countries of the Mediterranean are not the only 
ones whicK have developed systems of roads. 
The ancient civilisations of Mexico and Peru 
had roads which we are told were in some in- 
stances not inferior to those of the Romans. 
The Incas of Peru had a magnificent system, 
extending to every part of their vast empire, 
but, as far as we can learn, they were largely, if 
not entirely, built to accelerate the movement 
of troops and supplies. So well did they also 
serve an economic purpose, however, that, prior 
to the advent of the white man, such a thing 
as famine was unknown in Peru. At stated 
intervals along the main road were tambus or 
caravansaries and storehouses, where provi- 
sions were collected for the soldiery, so that the 
passage of troops never entailed any additional 
hardship on the people along the way. These 
roads also served as a system of post roads for 



16 EOADS, PATHS AND BRIDGES 

the rapid transmission of government dis- 
patches. About every five miles were sta- 
tioned runners selected for their speed, endur- 
ance and reliability, who acted as carriers. 

The most magnificent of the Peruvian roads 
was the great mountain highway between the 
two capitals, Quito and Cuzco, of which only a 
few fragments remain to-day. The younger 
Pizarro on first obtaining sight of it exclaimed : 
** Nothing in Christendom equals the magnifi- 
cence of this road across the Sierra.'' Hum- 
boldt, who viewed the remains in the beginning 
of the 19th century, said; *^ Nothing I have 
seen of the remains of Eoman roads in Italy, in 
the south of France and in Spain, was more 
imposing than the works of the ancient Peru- 
vians, which were, moreover, situated at an 
elevation of more than 13,000 feet above the 
level of the sea ; ' ' while Cieza, who saw the road 
about 1540, compares it to the Roman road in 
Spain at that time, which was known as the 
** Silver Road." The length of this magnifi- 
/ cent road is variously estimated at from 1,500 
I to 2,000 miles, or five or six times the length 
\ of the completed Appian Way. The breadth 

\ 



HISTORY OF ROAD BUILDING 17 

of the road scarcely exceeded 20 feet. Near 
Cuzco we are told tliat there was a stream of 
water and shade trees on either side, while 
stone pillars at regular intervals, similar to 
European milestones, marked the distances. 
Besides the regular tambus there were also at 
frequent intervals smaller buildings exclusively 
for the accommodation of travellers. 

The construction was ingeniously varied with 
the requirements of the region traversed. Por- 
tions greatly exposed to destructive agencies 
were paved with massive blocks of well-cut 
stone, sometimes as much as 10 feet wide. 
Other regions were paved with a substance not 
unlike bituminous macadam, which Humboldt 
says ''time has made harder than the rock it- 
self.'^ Wide rivers in deep canyons were 
crossed on suspension bridges composed of 
fibre, some of them being more than 200 feet in 
span. In the adaptation of roads to natural 
conditions, the Peruvians were superior to the 
Romans. Instead of clinging to the straight 
line, the Peruvian roads were adapted to the 
topography of the country. No avoidable as- 
cents were made. Unavoidable precipices were 



18 EOADS, PATHS AND BEIDGES 

scaled by means of steps, and since wheeled 
vehicles were unknown and the llama was the 
universal beast of burden, this was no serious 
obstacle to travel. 

Mediceval Neglect and Its Consequences, — 
With the fall of the Eoman Empire, its mag- 
nificent system of roads passed into disuse and 
neglect. With Charlemagne came a slight re- 
vival, but the economic and political conditions 
were such as to make this impulse of but short 
duration, and the country soon lapsed into 
feudalism. Each little community depended 
upon itself for the necessities of life. Com- 
merce was practically abandoned. The roads 
came to be looked upon with dread, and as being 
simply avenues upon which the robber barons 
might at will swoop down for plunder and 
rapine. Seclusion and inaccessibility came to 
be considered as in a measure essential to 
safety. In many places the roads were torn up 
and destroyed in order to prevent the easy in- 
gress of robbers and marauders. The little 
travel done was on foot or horseback, along 
narrow paths or trails. 

At this period the old Eoman highways had 



HISTOEY OF EOAD BUILDING 19 

sunk into the marshes or been overgrown by 
forests, and such other roads or paths as ex- 
isted are described as having been '4n a state 
of nature, or worse.'* A road was simply a 
right of way, an unimproved path from one 
hamlet to another. Almost all goods were 
transported by packhorses. In some parts of 
the country wheeled vehicles were entirely un- 
known. If the road was extraordinarily bad, 
the traveller left it and travelled in the adjoin- 
ing field or wood. 

At the end of the eleventh century came the 
first crusade, which was followed during the 
next two hundred years by seven other similar 
movements of greater or less magnitude. 
Though they failed of their original object, the 
crusades were of immense value to the whole 
of Europe, in that they promoted intercourse 
between the nations, awakened them from their 
lethargy, and stimulated commerce and the dis- 
semination of knowledge. In order that it 
might be possible to move armies toward Syria, 
towns made grants, and kings and popes con- 
tributed money and issued edicts for the im- 
provement of highways. 



20 EOADS, PATHS AND BRIDGES 

Revival of Road-Making in Europe. — Com- 
mencing with Louis XII in 1508, successive 
kings appointed road overseers for tlie king- 
dom of France. These officers bore various 
titles at different times. In general, however, 
they were charged with the duty of inspecting 
the *^ King's Highways" and repairing them. 
Even at this early time the French roads seem 
to have been divided into two classes : viz., those 
main lines between cities, known as the King's 
Highways, and the minor crossroads, under the 
charge of the nobles through whose territory 
they ran. It appears to have been about the 
beginning of the sixteenth century that some 
systematic repairs on roads were begun, though 
for another 150 years nothing more than filling 
up the worst holes was attempted. 

In the reign of Henry IV France emerged 
from mediaevalism. Sully, who was appointed 
Comptroller of Finance in 1597, was also made 
Grand Voyer or Great Way- Warden of France. 
Owing to the interest this first of the great min- 
isters took in agriculture, a beginning was made 
in the improvement of the roads through the 
rural districts. Up to that time France had 




HOLLAND- S HIGHWAYS. 



1. Taking milk to town over a country road in the Netherlands. 
2. An interiirban road in Holland, made of slag-brick; a cycle- 
path and shaded walk on the left and a bridle-path on the right. 



HISTORY OF ROAD BUILDING 21 

not had a smooth, hard roadway since the Ro- 
man supremacy. A few, such as the road 
from Paris to Orleans, had a roughly paved 
causeway in the centre, but such was the con- 
dition that all travel was necessarily by horse- 
back. In the winter it was almost impassable 
by any means. Under Sully, and later under 
Richelieu, slow progress was made in bettering 
the condition of the roads. At the beginning 
of the seventeenth century broken stone began 
to be applied to the roads for their improve- 
ment. In 1661 Colbert was appointed Comp- 
troller of Finance, which office carried with it 
the superintendence of highways. During his 
ministry 15,000 miles of hard road were con- 
structed. Such a great work was not accom- 
plished without a corresponding hardship to the 
people. The old feudal institution of the cor- 
vee was used to an extent hitherto unknown. 
The peasantry were taken long distances from 
their homes and kept at work on the roads even 
during seeding and harvest times. Rioting and 
insurrection were provoked in various parts of 
the kingdom, and the condition of the people be- 
came almost unendurable. This system pre- 



22 EOADS, PATHS AND BEIDGES 

vailed with the utmost rigour until 1774, when 
Turgot, who was then Minister of Finance, re- 
lieved it of its worst features, but it was not 
finally abolished until 1787, when the nation was 
on the brink of revolution. 

The present magnificent road system of 
France was really founded by Napoleon. He 
built many roads through the empire, among 
others the famous road over the Simplon Pass 
in Switzerland, which was commenced in 1800, 
and required six years for completion. The 
road work of France was systematized and 
placed in the hands of a competent and per- 
manent body of engineers, and, in order to raise 
funds for the continuance of this work. Napo- 
leon attempted to establish a toll system on the 
best roads. Owing to the determined opposi- 
tion of the people, however, the idea was soon 
abandoned. From this time on road improve- 
ment has been extremely popular in France and 
the people have willingly submitted to the neces- 
sary taxation. 

In 1775 the great French engineer Tresa- 
guet published his first treatise on broken- 
stone roads. Too much credit can not be given 



HISTORY OF EOAD BUILDING 23 

to the work of Tresaguet. He was the real 
father of modern road building and mainte- 
nance, as his work preceded that of McAdam 
and Telford by about forty years. 

Pierre-Marie-Jerome Tresaguet was bom at Nevers, 
France, in 1716, and was made Chief Engineer in 
the District of Limoges, July 22, 1764, at a salary of 
2,400 francs ^($480) per annum. His duties con- 
sisted iQ supervising the construction and mainte- 
nance of bridges and highways in the District, and 
it was here that he conducted his most important 
work. On April 19, 1775, he was made Inspector 
General, at a salary of 3,600 francs ($720) per an- 
num, and 2,400 francs ($480) for travelling expenses. 
Later on in the same year, he was made a member 
of the Commission of Inspectors General of France, 
but he continued his duties at Limoges for about two 
years. He became very famous, and in 1785 he en- 
deavoured to introduce his system in Paris. About 
this time, however, he fell sick, and his great worth 
was recognised by his being awarded a pension of 
3,000 francs ($600). During the French Revolution 
this pension was reduced, and, at the age of 80 years, 
he found himself reduced to the direst poverty. In 
that year the commune of Paris was called on to give 
this eminent engineer three pounds of meat daily. 
He died in the same year. 

In his report to the Assembly of Bridges 
and Highways in 1775, Tresaguet pointed out 



24 EOADS, PATHS AND BEIDGES 

that, although the ancient highways were of a 
thickness of eighteen inches in the middle and 
twelve inches at the sides, in six months they 
were cut with deep ruts, because of the lack of 
maintenance. He suggested reducing the 
depth of material in the centre to ten inches, 
and that the sides be sloped at an angle of about 
20 degrees. TresagTiet laid great stress on 
systematic, continuous maintenance as against 
intermittent and irregular repairs. It was he 
who organised the canton, or patrol system, 
which has made the French roads the most 
superb in the world. 

Development of Road Building in England, — 
The first record of road legislation in England 
bears the date of 1285, and provides that the 
trees and bushes on both sides of the road for a 
distance of 200 feet shall be cut away to pre- 
vent robbers from lurking therein and rushing 
upon their victims unawares. It further pro- 
vides that when a road is worn deep another 
shall be laid out alongside. 

This latter provision was slightly modified by 
Henry VIII about 250 years later, who provided that 
*'two justices of the peace and 12 other men of 



HISTORY OF EOAD BUILDING 25 

wisdom and discretion shall choose fresh routes when 
the old ones are worn out." In 1346 Edward III 
authorised the first toll to be levied for the repair 
of roads. This commission was granted to the Master 
of the Hospital of St. Giles and to John Holborn, 
authorising these parties to levy toll on vehicles pass- 
ing on the road leading from the hospital to the Old 
Temple of London, and also on an adjoining road 
called the Portal. In 1523 Parliament passed its 
first act relative to the repair of roads, but it was 
not until near the middle of the 18th century that 
highway legislation became active. 

The condition of the streets and roads of 
England was indeed deplorable during this 
time. Street pavements developed somewhat 
earlier than rural roads, but even their im- 
provement was extremely slow. As late as 
1190, we are told that a wind-storm unroofed 
the church of St. Mary-le-Bow, Cheapside, Lon- 
don, and four pillars 26 feet long, falling verti- 
cally in the street, sank by their own weight, so 
that only four feet remained above the mud. 
These were certainly not very inviting streets 
for either pleasure or business. Still, it was 
not until 1532 that the first statute for paving 
in London was recorded. 

In this modest act the streets are described 



26 KOADS, PATHS AND BEIDGES 

as ^^very foul and full of pits and sloughs, so 
as to be mighty perilous and noyous as well 
for all tlie King's subjects on horseback as on 
foot with carriages." Nor did this condition 
change rapidly. Writing in the year 1770 Mr. 
Arthur Young, after a six months ' tour through- 
out northern England, says of the turnpike to 
Wigan : 

*'I know in the whole range of language no terms 
sufficiently expressive to describe this infernal road. 
Let me seriously caution all travellers who may acci- 
dentally propose to travel this terrible country to 
avoid it, as they would the devil, for a hundred to 
one they break their necks or their limbs by over- 
throw or breakings down. They will meet with ruts, 
which I actually measured, four feet deep, floating 
with mud only from a wet summer; what then must 
it be in winter? The only mending it receives is 
tumbling some loose stones into the worst holes, which 
serves no other purpose than jolting a carriage in the 
most intolerable manner. These are not only opin- 
ions, but facts; for I actually passed three carts 
broken down in those 18 miles of execrable memory. ' ' 

Still later Lord Macaulay informs us that 
the roads were so bad that in places the crops 
were allowed to rot in the fields, while only a 



HISTORY OF ROAD BUILDING 27 

few miles away people were actually dying of 
starvation. "With such roads, a few miles 
were a more effective barrier than the oceans 
are to-day. Not only was commerce practically 
impossible, but even the news of dearth or 
plenty could travel but slowly. 

The legislative effort to better the condition 
of the English roads expressed itself in a com- 
prehensive system of turnpike acts. It is es- 
timated that in 1838 about 1,100 of these turn- 
pike trusts were in existence throughout the 
kingdom. They proved of little permanent 
value, however. Not only their construction, 
but also maintenance was often defective. The 
cost of collecting the tolls often nearly equalled 
the income, leaving little or nothing for main- 
tenance. In 1871 the census showed that 5,000 
persons in England and Scotland were engaged 
in merely collecting tolls. In 1857 Ireland freed 
herself from toll gates, and tolls were abolished 
in England by act of Parliament, passed in 
1878. 

McAdam and Telford, — No historical sketch 
of the highways of England would be complete 
without at least a mention of the two great en- 



28 EOADS, PATHS AND BRIDGES 

gineers, Jolin Loudon McAdam and Thomas 
Telford. 

John Loudon McAdam was born at Ayr, 
Scotland, September 21, 1756, and spent his 
boyhood in New York. He returned to Scot- 
land in 1783, and from that time until 1798, he 
was Trustee of Roads and Deputy Road Lieu- 
tenant of Ayrshire. In 1798 he moved to Eng- 
land and was made Superintendent of Roads of 
the Bristol District in 1815. He made a most 
exhaustive investigation of roads in England, 
and he is said to have travelled 30,000 miles and 
spent more than five years and £5,000 in in- 
vestigating the English roads. He made a re- 
port in 1811 to a committee of the House of 
Commons, outlining his system. In 1827 he 
was made General Surveyor of the Metropoli- 
tan Roads, and m recognition of his success in 
improving them, he received a grant of £10,000 
from the British Government. His methods 
are set forth in the chapter on macadam roads 
in some detail. McAdam died at Moffat, in 
Dumfriesshire, November 26, 1836. He wrote 
two books, which have become classics in road- 
building. They are: *'A Practical Essay on 





o 

O 

Eh 



HISTORY OF ROAD BUILDING 29 

the Scientific Repair and Preservation of 
Roads ^' (1819), and 'Present State of Road- 
Making'' (1820). 

Thomas Telford, a civil engineer, was born 
August 9, 1757, at Eskdale, Dumfriesshire, and 
was the son of a shepherd. At the age of fif- 
teen he was apprenticed to a stone mason at 
Langholme, where he had an opportunity to 
gain an acquaintance with Latin, French and 
German. As a young man, he was fond of writ- 
ing poems, a number of which were published, 
although they were of comparatively little value. 
In 1780 he went to Edinburgh, where he was em- 
ployed in the erection of houses, and occupied 
much of his time in learning architectural draw- 
ing. In 1782 he went to London and found 
employment in the erection of Somerset House. 
This was followed by other work of a similar 
character, which eventually resulted in his ap- 
pointment as Surveyor of Public Works for the 
county of Sallop. His first bridge was finished 
in 1792. Later on he was employed in the con- 
struction of some of the most important canals 
in Great Britain, and was consulted in 1806 by 
the king of Sweden regarding the construction 



30 EOADS, PATHS AND BRIDGES 

of the great Gotha Canal, for which his plans 
were adopted. In 1803 he was appointed en- 
gineer for the construction of 920 miles of road 
in Scotland, most of which was through difficult 
country. He also built a system of roads in 
the most inaccessible parts of Wales, where he 
built a most magnificent suspension bridge 
across the Menai Straits. He also built an im- 
portant road for the Austrian Government 
from Warsaw to Brest. He did very impor- 
tant work in the improvement of harbors, and 
was generally looked upon as one of the most 
eminent engineers of his time. His great work 
in the building of roads and bridges has given 
him the most lasting fame, and a type of road 
which is now quite frequently built on marshy 
or unstable ground is known as the Telford 
road. 

Early Road Work in the United States, — 
America, as an abode of the white man, was 
still young when she entered the field of road 
building and road legislation. The first Amer- 
ican road law was passed by the House of 
Burgesses of Virginia in 1632. So far as can 
be ascertained, the first American road built by 



HISTOEY OF EOAD BUILDING 31 

white men was at Jamestown a few years later. 
We can imagine tlie conditions somewhat, 
both as to means of communication and trans- 
portation, when we learn that in 1625, when the 
British Crown took over Virginia from the 
London Company, the inventory revealed the 
interesting fact that the Governor alone had a 
horse. 

In the North the so-called New England Path, be- 
tween Boston and Plymouth, was begun in 1639. In 
the province of New York, regulations for road build- 
ing were passed in 1664, and two years later the first 
Maryland road law came into existence. Pennsylvania 
followed some years later (1692) with a road act 
placing the control of the highways in the hands of 
the townships which, however, was amended eight 
years later, whereby the control was given over to 
the counties. To Pennsylvania is also given the 
credit of the first important macadam road built in 
America — the Lancaster turnpike from Lancaster to 
Philadelphia — which was constructed in 1794. Por- 
tions of this road are still operated as a toll road. 

The extent and character of these early roads may 
perhaps be judged more clearly from the state of the 
postal service. It was not until 1673 that a post 
service was established between New York and Bos- 
ton, and three days were required for the trip. 
Twenty-two years later, in 1695, letters were for- 



32 EOADS, PATHS AND BEIDGES 

warded only eight times a year from the Potomac to 
Philadelphia. In 1717 mail from Boston to Wil- 
liamsburg, Virginia, was delivered every four weeks 
in summer and every eight weeks in winter, and as 
late as 1790, the number of post-offices in the United 
States numbered only 75. 

Thus, at the time of the organisation of our 
Government, highway construction can scarcely 
be said to have begun. The few roads, if they 
may be dignified by such a name, were mostly 
the result of chance — mere trails which had 
gradually been widened to admit the passage 
of vehicles, but were usually almost impassable 
during long periods. Systematic organisation 
for either construction or maintenance did not 
exist, and each little community was left to cope 
with the problem as best it could. 

Civilisation was rapidly pushing toward the 
great West, however, and the need of roads be- 
came imperative. 

The first wagons crossed the Alleghanies within 
two years after the close of the War of the Revolu- 
tion. The need for better roads had now become so 
strong that private capital was attracted and numer- 
ous toll roads were constructed throughout the dif- 
ferent States. By 1828 nearly 2,380 miles of these 



HISTOEY OF EOAD BUILDING 33 

roads had been constructed in Pennsylvania alone, 
at a cost of $8,431,000. Few, if any, of the turn- 
pikes returned sufficient dividends to make them a 
profitable investment, as one of the chief drawbacks 
was the high cost of maintaining toll gates and col- 
lecting the tolls. Nor did the turnpikes suffice to 
fill the demands of the time. In 1821 the cost of 
transporting a barrel of mackerel from Philadelphia 
to Somerset was $8 per hundred pounds, and from 
Philadelphia to Pittsburg the rate was $11, or 70 
cents per ton-mile. Not until about 1865 were the 
railroads of sufficient extent to make themselves felt 
as considerable factors in the wholesale reduction of 
long-distance freight rates. By this time the charge 
for hauling freight from Baltimore to Wheeling on 
the turnpike road was reduced to 17 cents per ton- 
mile. 

Our national legislators early recognised the 
need of adequate means of communication and 
transportation, and after a lengthy debate an 
act was passed in 1806 providing for the build- 
ing of a great highway from the Atlantic to 
the Mississippi. Beginning at Cumberland, 
Md., on the Potomac, this great highway passed 
through the States of Maryland, Pennsylvania, 
Ohio and Indiana, westward to the Wabash and 
the Mississippi. For thirty-two years the Gov- 
ernment struggled with this great enterprise 



34 EOADS, PATHS AND BEIDGES 

until finally the appropriations ceased alto- 
gether in 1838, and the work was discontinued 
after an expenditure of $6,824,919.33 appropri- 
ated by Congress. 

President Monroe once vetoed the appropriations 
for the National Turnpike, as well as a bill introduced 
by John C. Calhoun, providing for setting aside the 
dividends from the National banks for road purposes. 
Revenues derived from the sale of public lands, how- 
ever, continued to be set aside by Congress for aid 
in road construction. Between 1811 and 1845 Lou- 
isiana, Indiana, Mississippi, Illinois, Missouri and 
Iowa were aided in this way to the extent of about 
$5,000,000. Between 1854 and the beginning of the 
Civil War Congress appropriated in all something 
like $1,600,000, which was expended chiefly on roads 
within the territories. Thus, up to 1861, the National 
Government had assisted in road building throughout 
the Nation to the extent of about $14,000,000. 

Since 1861 the National Government has 
rendered aid to road building only in an edu- 
cational sense. For a time following the war 
the immense debt incurred made appropria- 
tions from the National treasury almost out 
of the question, and besides, the idea had be- 
come quite prevalent that the railroads had 
lessened the need as well as value of improved 



HISTORY OF ROAD BUILDING 35 

roads. It required some time for the country: 
to discover tlie error and it was not until the 
advent of the bicycle that the good-roads move- 
ment awoke from its lethargy. 

Government Aid. — An office of road inquiry 
was established under an act of Congress, ap- 
proved March 3, 1893, making an appropriation 
of $10,000 to the Department of Agriculture for 
making inquiries in regard to systems of road 
management throughout the United States and 
for making investigations in regard to the best 
methods of road-making, preparing didactic 
publications on this subject, and assisting the 
agricultural colleges and experiment stations in 
disseminating information. 

The work of the office was at first of neces- 
sity very limited. In 1897 the construction of 
short sections of sample roads under the super- 
vision of skilled road builders was begun in a 
small way in co-operation with the various agri- 
cultural experiment stations. In December, 
1900, a laboratory for testing the physical 
qualities of different road-building materials 
was added. Two years later the annual ap- 
propriation was increased to $20,000, and pro- 



36 EOADS, PATHS AND BEIDGES 

vision was made for the investigation of the 
chemical and physical character of road materi- 
als. The language of the appropriation bills 
has remained practically unchanged up to the 
present time, except that the name of the office 
was changed from Public Eoad Inquiries to the 
Office of Public Eoads, and a statutory organisa- 
tion provided in the agricultural bill, approved 
March 3, 1905. 

From this modest beginning the work of the 
office has gone along in a careful and conserva- 
tive manner. 

Local communities can easily avail themselves of 
the assistance granted by the United States Office of 
Public Roads. It is necessary only for the local au- 
thorities having jurisdiction over the roads to make 
application either to the Secretary of Agriculture or 
the Director of the Office of Public Roads for the 
assignment of an engineer or expert to investigate 
local conditions with reference to the roads, and to 
give such advice and instruction as may be necessary. 
The salary, and in most cases the expenses, of such an 
engineer are paid by the National Government, and 
hence his services are free to communities. The 
road-material laboratories of the Office of Public 
Roads make tests to determine the relative value of 
road material, without cost to any citizen of the 



HISTORY OF ROAD BUILDING 37 

United States who will take the trouble to write to 
the Office and obtain the necessary forms and ship- 
ping blanks for submitting samples of material. The 
only expense to be borne by the private individual is 
the transportation charge on the material to the 
Office. 

Within recent years the investigative work 
of the Office of Public Roads has attracted 
world-wide attention, and the testing laborator- 
ies are looked upon as equal to, if not superior 
to, any. in existence. 



CHAPTER II 

EOAD LEGISLATION AND 
ADMINISTEATION 

While in its strict interpretation a principle 
is defined as a fundamental truth or doctrine, 
we are at liberty, in dealing with this subject, to 
regard a policy which has been followed by 
many agencies over long periods of time and 
with successful results as being fundamental, 
and, therefore, to be considered in the light of a 
principle. 

Applying this reasoning to the information 
afforded by the histories of the road systems of 
all countries, it becomes evident that one of the 
features common to all of the successful road 
systems of history is centralisation of authority 
and responsibilities. The most striking exam- 
ple illustrating the power of centralisation is 
afforded by the splendid roads of Rome. No 
sooner had the power of the imperial city crum- 
bled away and the management of her splendid 

38 



ROAD LEGISLATION 39 

roads passed into the hands of many nations 
than the roads began to deteriorate, because of 
the utter absence of attention. The most con- 
spicuous example in modern times of an efficient 
system of roads well constructed, maintained 
and administered is the road system of France. 
Beginning with the humble patrolman, the sys- 
tem provides definite lines of authority through 
various grades upward to the Inspector-General 
at Paris, whose guiding hand directs the whole 
organisation, prevents duplication of effort and 
co-ordinates all efforts and all accomplishments 
In the United States the States which have 
made most progress in the actual improvement 
of the public roads are those which have in some 
degree centralised the construction and care of 
the roads in a State official or officials. 

Until comparatively recent years most of the 
States of the Union have followed a policy di- 
rectly opposed to the policy of centralisation. 
The laws all provided, and in many States 
continue to provide, for a large number of 
officials, each having a very limited territory 
under his control, and each being, in a measure, 
independent of any direct supervision. This 



40 EOADS, PATHS AND BRIDGES 

policy of extreme localisation has, by its very 
failure to produce adequate results, confirmed 
the wisdom of a centralised system. 

In the light of this evidence it seems clearly 
demonstrated that each State should provide a 
centralised direction of its road work, and, 
pending that time, each county should, as far as 
possible, centralise the control of its road work 
in a competent official, and, carrying this reason- 
ing still further, it is safe to say that each 
township could with profit place its work under 
the direction of a competent employe or official 
rather than to depend upon a number of officials 
whose authority is not defined and whose duties 
overlap. 

A second important point which has been 
brought out clearly by the experience of all na- 
tions, and which has been emphasised most 
strongly since the development of modern traffic 
conditions is the necessity for special knowl- 
edge and skill on the part of the men who 
actually build and maintain the roads. It is a 
curious fact that, although the public road is 
conceded to be so important to humanity as to 
be classed with the home, the church, and the 



EOAD LEGISLATION 41 

school, and although its condition directly 
affects the welfare of all who are called upon to 
traverse it, and indirectly all who are dependent 
upon the products which are transported upon 
it, few people give more than a passing thought 
to the methods by which the road is built and 
maintained, while it is an inborn conviction on 
the part of nine men out of ten that they are 
thoroughly competent to say how a road should 
be built and maintained. If the general public 
would consider that to build a successful road 
a suitable location must be found, grades re- 
duced where necessary, a drainage system pro- 
vided, suitable material selected, foundation 
and surface arranged with great exactness, cul- 
verts and bridges constructed, and, to meet 
modern traffic conditions, the whole subject of 
bituminous and other special binders dealt with 
from the standpoint of the expert, there would 
be more inclination to employ for such work 
men who make a profession of highway en- 
gineering. It is very difficult to find in any of 
the road laws of this country, except those that 
provide for State Highway departments, any re- 
quirement that the officials having charge of the 



42 EOADS, PATHS AND BEIDGES 

road work shall possess any special qualifica- 
tions. Hence the enormous waste of public 
funds through ignorance of correct methods, as 
well as from the lack of centralised authority. 
Skilled supervision is an essential in road work, 
and should be considered a fundamental re- 
quisite applicable at all times, under all con- 
ditions, and by all units of government. It is 
just as necessary for the township to employ a 
man with a knowledge of road building rather 
than one who has no knowledge of the subject, 
as it is for the State to require its highway eur- 
gineer to be competent and experienced. 

Roads Belong to the Public, — That the roads 
belong to the public and that their use and con- 
trol should remain with the public is a principle 
recognised by Eome in the management of her 
great system of highways, and which has per- 
sisted in all of the civilised countries of Europe, 
and has finally been recognised throughout the 
United States, in spite of costly and elaborate 
experiments with the toll-road system, particu- 
larly in England and in this country. The 
Eomans never approved the plan of giving over 
any of the public roads to the control of private 



EOAD LEGISLATION 43 

individuals or companies, and few, if any, tolls 
were ever collected on Roman roads. The Eng- 
lish Parliament in the latter part of the eight- 
eenth century passed innumerable turnpike acts, 
and for a good many years during the eighteenth 
and nineteenth centuries the toll-road system 
was supreme in England. It broke down under 
the fierce resentment of the public, and because 
it was costly and clumsy in operation. The cost 
of collecting the tolls was totally out of pro- 
portion to the amount actually spent in main- 
tenance. Toll roads were abolished finally in 
Great Britain in 1878. In this country the be- 
ginning of the nineteenth century witnessed 
very great activity in the building of pikes or 
toll roads. Here, however, as in other coun- 
tries, the experiment proved unprofitable and 
contrary to the public welfare, with the result 
that this system has been gradually abandoned, 
until at the present time the toll road is de- 
cidedly the exception rather than the rule in 
the United States. The toll system is funda- 
mentally wrong because it places under private 
control that which must of necessity be a public 
utility; it places the burden of taxation solely 



44 EOADS, PATHS AND BEIDGES 

upon the users of the road, and leaves untaxed 
those who benefit materiallj from the improve- 
ment of the road, although having no occasion 
to make use of it for travel. An example of this 
is to be found in non-resident owners of tracts 
of land abutting the road and increasing in 
value by reason of the improvement. Finally 
the toll system is unprofitable to the stockholder 
and excessively burdensome to the traveller, be- 
cause of the great cost of collecting the tolls and 
conducting the system, which makes the divi- 
dend low to the stockholder and the rate high to 
the traveller. 

Personal Service on Roads Inadvisable. — 
From ancient times the practice has been gen- 
eral among all nations to compel personal serv- 
ices on the roads, or to accept personal services 
in lieu of a cash tax. Under the ancient des- 
potic monarchies slave labour was largely used, 
and under the Bourbons of France the peasants 
were compelled to contribute a number of days * 
work on the public roads. Modern standards 
of humanity discountenance these rigorous 
methods, but thuy exist in another form through 
what is known as the statute-labour system. 




PRIMITIVE METHODS OF TRAXSPORTATIOX. 




A TOLL-HOUSE OX THE XATIU.nal KUAD. 



EOAD LEGISLATION 45 

Under this system the laws require that each 
able-bodied citizen perform a given number of 
days' service upon the road, or commute this 
labour tax in cash, while in many States of the 
Union, even the taxes that are payable in cash 
may be paid in labour at a given rate per day. 
This inadequate system is entirely out of 
harmony With modern business practice and 
modern governmental policies. It provides un- 
trained labourers who are not amenable to dis- 
cipline and who render their services grudgingly 
and in as scant a measure as possible. They 
are at the same time employers and employes, 
because it is by their votes that the road offi- 
cials are kept in power. In consequence they 
dominate their leaders and the results which 
they accomplish are almost negligible. Hence 
it has come to be essential to efficiency in the 
administration of our public roads that all road 
taxes be paid in cash, so that regular employes 
may be obtained, who may be required to give a 
full and honest day^s work, who may acquire 
the skill essential to efficiency, and who may be 
answerable to reasonable discipline. We can 
hardly consider it, however, a maxim that road 



46 EOADS, PATHS AND BEIDGES 

taxes should be paid in cash, regardless of all 
conditions. It has been claimed that in some 
of the Southern States it is impossible to collect 
cash taxes, and the only recourse is to compel 
personal services on the part of a large element 
of the population. It must be understood that 
such examples constitute exceptions, and that 
recourse to the payment of road taxes in labour 
is justified only in extreme cases. 

The problem of what to do with the convicts 
and other offenders against society has been 
one which has vexed the students of sociology 
for centuries, and it is now universally conceded 
that idleness is extremely detrimental to the 
prisoner, and by reason of his unproductive- 
ness, burdensome to the public. Outdoor pro- 
ductive labour is conceded to be beneficial to the 
prisoner mentally, morally, and physically, and 
to make possible a return to society for its out- 
lay. As to the character of work which should 
be performed by the convict, it is reasonable to 
assert that as the prisoner has offended against 
the public, his labour should be for the benefit 
of the public, and directed toward public im- 
provements. In this way, he is not only pro- 



EOAD LEGISLATION 47 

moting the public welfare, but he is also enter- 
ing into competition to the least possible degree 
with honest free labour. The volume of public 
improvements is necessarily limited, and com- 
prises, among other improvements, the construc- 
tion of roads and the preparation of road mate- 
rials. Certainly no public improvement upon 
which the^ convict can be employed will yield a 
greater amount of benefit to the public than the 
improvement of the roads, and wherever this 
form of labour is applicable, it should be em- 
ployed. In the South excellent results have 
been obtained by using convicts in actual con- 
struction of roads. In some other States the 
convicts have been employed in stockades in the 
preparation of road materials. Conditions are 
such in some of the States as to make the wis- 
dom of using convicts in this way questionable, 
but the plan should not be rejected without the 
most thorough consideration. 

Roads More Than Local Institutions, — By 
reason of the many inventions of modem times 
which have tended to shorten distance and time, 
which have enormously increased manufactures, 
and which have made possible the concentration 



48 EOADS, PATHS AND BEIDGES 

of a large percentage of our population in cities, 
and because of the growth of education, the gen- 
eral dissemination of learning, and the broader 
field of knowledge afforded to the people of civ- 
ilised nations in the present day, the isolation 
of local communities has been largely super- 
seded by the intercommunication and interde- 
pendence which link together communities hun- 
dreds of miles apart. The road is no longer a 
merely local institution, for over it must be 
transported the food products which are neces- 
sary for the existence of the city dwellers, and 
the manufactured products which come from 
the city to the country dwellers. This road 
may be traversed by the automobilists from 
other neighbourhoods and other States, and by 
the transient guests of the summer hotels and 
resorts. The condition of this road affects the 
welfare, not only of the people who live near it, 
but of all those other classes of people who have 
occasion to buy the products of the surrounding 
country, or to sell to the inhabitants, or to make 
use of the road as transients. This condition 
has given increasing importance to the maxim 
that all who share the benefits of road improve- 




DESTROYERS OF PROPERTY 



]. A mudhole on a r "ci in ;i Vii';'j,ini 1 township which voted down 
a bond-issue. 2. A hill road in another short-sighted community. 
3. Ruined wagons about a blacksmith shop where roads are unimproved. 



EOAD LEGISLATION 49 

ment should share the burdens incident to such 
improvement. This maxim has found concur- 
rent expression in the establishment of State 
highway departments and the appropriation of 
State funds to aid in the improvement of the 
main travelled roads. State aid is justified, not 
only on the ground that it distributes the bur- 
dens in proportion to the benefits, but also be- 
cause it provides a centralisation of authority, 
skilled supervision, and the public control al- 
ready referred to as essentials, and as a result 
of these factors, economy, co-ordination and 
tangible results in the way of construction and 
effective maintenance follow. 

Importance of Systematic Maintenance, — 
Effective maintenance of the roads is rather a 
result than a system and, if the other essentials, 
namely, centralised skilled supervision, cash tax- 
ation, public control, and the utilisation of con- 
vict labour, be adopted, it is probable that 
effective maintenance will follow. It is well to 
state here, however, that almost without excep- 
tion no provision has been made in the United 
States for the maintenance of roads, even those 
which are most perfectly constructed and which 



50 EOADS, PATHS AND BEIDGES 

would, therefore, seem to justify some outlay 
for the maintenance of their high state of effi- 
ciency. It is just as careless and unwise to 
leave a good road uncared for as it is to leave a 
well-constructed building to the mercy of the 
elements and depredations of the public. The 
strongest feature of the French road system is 
the constant care of the roads which have already 
been constructed. The whole system of main 
roads is divided into short sections of from 2% 
to 5 miles approximately, and each section is in 
charge of a patrolman, who gives his entire time 
to the road, repairing slight defects as soon as 
they occur, keeping the ditches open, trimming 
the trees and bushes, removing dust and de- 
posits of sand and earth after heavy rains, and, 
when ordinary work is impossible, he prepares 
stone and transports it to where it is needed. 
In order to facilitate this repair work quantities 
of crushed stone and gravel are placed at con- 
venient intervals along the road, while to meet 
the expense of this maintenance annual appro- 
priations are made, based upon careful esti- 
mates by the engineers in charge. Mainte- 
nance, to be effective, must be systematic or in 



EOAD LEGISLATION 51 

accordance with some definite plan or pnrpose, 
and must be continuous, instead of at long in- 
tervals, as we practise it in this country. 

Financing Public Roads, — The methods of 
financing road improvement constitute a very 
important part of the subject. Eliminating as 
unwise and impracticable the toll system and, 
except in extreme cases, payment of road taxes 
in labour, it follows that there are only four 
ways of obtaining revenues for improving the 
roads, namely, a cash property tax, a poll tax, a 
bond issue, and a State appropriation, the latter 
of which may be derived from one or many 
sources. There may be special methods of ob- 
taining revenue which are applicable only in 
special cases, such, for example, as private sub- 
scription, the sale of public property, the appro- 
priation of certain license taxes, etc., but as a 
general proposition the four sources of revenue 
already named must be depended upon. It is 
manifest that State aid cannot be given in suffi- 
cient amount to meet the needs of the respective 
counties. Poll taxes may not be available, as 
the law may provide that they be expended for 
other than road improvement. Even where this 



S2 ROADS, PATHS AND BRIDGES 

form of revenue is available, it is usually neces- 
sary to supplement it with some other form of 
revenue. This brings us to the consideration of 
the relative advantages of making only such im- 
provements as may be possible by means of an 
annual cash tax, and the making of improve- 
ments on a large scale by means of a bond issue. 
It may be said in favour of bond issues that they 
bring immediate returns in the form of im- 
proved roads and in such amount as to enable a 
large proportion of the population to enjoy the 
benefits of this improved medium of transporta- 
tion without having to wait a long period of 
years. The improvement necessarily develops 
the resources of the locality more quickly and 
thereby increases wealth. The cost per mile of 
road is lowered by reason of the magnitude of 
the enterprise, while the cost of maintenance is 
materially decreased because it is easier to 
maintain a long stretch of improved road con- 
necting two communities than it is to maintain 
short sections of improved roads, the ends of 
which ravel or disintegrate more quickly be- 
cause of the fact that the remainder of the road 
extending from each end of the improved sec- 



EOAD LEGISLATION 53 

tion remains imimproved. A bond issue gen- 
erally places upon the next generation a portion 
of the burden, but this is contended to be equita- 
ble by reason of the fact that the wealth thus 
developed inures to the benefit of the generation 
called upon to bear a portion of the burden. 

A bond issue should never be considered a 
wise undertaking simply because it is a bond is- 
sue, nor should it be considered unwise for the 
same reason. The needs of the community in 
the way of improved roads, the financial condi- 
tion of the community, the necessary outlay to 
obtain this improvement, and the probable re- 
sultant benefits, compared with the resultant 
burdens, should always be considered. The 
Office of Public Eoads of the United States De- 
partment of Agriculture maintains a corps of 
engineers who are qualified to examine local 
conditions intelligently, and recommend a plan 
of improvement and outlay commensurate with 
the needs and the ability of the localities which 
they are called upon to advise. The services of 
these engineers are given free by the Govern- 
ment. Moreover, in many of the States having 
State highway departments, assistance of this 



54 EOADS, PATHS AND BEIDGES 

kind can be secured without cost. It is recom- 
mended, therefore, that the expenditure of large 
sums of money be based upon such careful and 
conservative advice. 

Road Economics. — Economics deal with that 
phase of the road subject which has to do with 
the relation between the outlay for road im- 
provement and the returns in the form of bene- 
fits. The question to be considered in all cases 
is not whether the outlay is large or whether the 
benefit is indirect, but whether the resultant 
benefit, either direct or indirect, is greater than 
the outlay. The amount to be expended can 
easily be ascertained by means of specific desig- 
nation and conservative estimates of the im- 
provements proposed to be made. The methods 
of providing the necessary revenues can be de- 
termined and the necessary administrative re- 
quirements made along the lines indicated in 
the preceding paragraphs. It remains, there- 
fore, to consider what benefits may be expected 
to arise from the proposed improvements, and 
what distribution of the improvements will af- 
ford the greatest amount of benefit to the great- 
est number of people. 



ROAD LEGISLATION 55 

In the first place the improvement of the road 
may be expected to lower the cost of hauling, 
greatly increase facilities for transportation, 
and add to the comfort of those who must use 
the road for these purposes. As a basis for 
considering this phase of the subject it may be 
stated that in 1906 the Bureau of Statistics of 
the Department of Agriculture obtained data 
which indicated the average cost of hauling to 
be 23 cents per ton-mile, and the average haul 
9%o miles. In the report issued by that Bureau 
it was stated that although ocean rates were 
higher than usual during the year 1905-1906, 
the mean charge for carrying wheat by regular 
steamship lines from New York to Liverpool 
was only 3%o cents per bushel, or l%o cents less 
than it costs the farmer to haul his wheat 9%o 
miles at 19 cents per ton-mile, from his farm to 
a neighbouring railroad station. Moreover, the 
cost for hauling wheat is less than the general 
average for all products. It is generally known 
that the load which two horses can draw on a 
smooth, hard road is double and sometimes 
treble the load which they can draw on an earth 
road. Engineers have made investigations on 



56 EOADS, PATHS AND BRIDGES 

this point which indicate that the difference in 
cost of hauling upon broken-stone roads, dry 
and in good condition, and an earth road con- 
taining ruts and mud, is the difference between 
8 cents per ton-mile and 39 cents per ton-mile. 
Since the introduction of motor vehicles this 
cost has been still further lowered, and a special 
demonstration of motor trucks in California 
yielded a rate of about 2% cents per ton-mile. 
It is manifestly impracticable to improve all of 
our roads by surfacing with hard material, but 
such an extensive improvement is unnecessary, 
because of the fact that repeated investigations 
have shown that 20 per cent, of the roads carry 
90 per cent, of the traffic. 

From the standpoint of the farmer, the in- 
creased loads which his team can draw, the pos- 
sibility of making a greater number of trips per 
day, and the decreased wear and tear on his 
team, his equipment and himself should furnish 
powerful arguments in favour of road improve- 
ment. 

Practical Value of Road Improvement. — In 
determining upon the location of proposed im- 
provements a careful traffic census should be 



EOAD LEGISLATION 57 

taken, so that tlie most heavily travelled roads 
may receive the most thorough improvement, 
and the other roads be improved according to 
their importance. 

Increase in the value of lands adjacent to the 
public road invariably follows a marked im- 
provement in the road. This increase is un- 
questionably genuine and not, as many persons 
claim, a fictitious increase arbitrarily assumed 
by the assessor, and which imposes upon them 
an unwarranted increase in taxation. If the in- 
crease were fictitious, the farm would have no 
greater market value than it had before. As a 
matter of fact the farm, if it were put upon the 
market, would command a better price than if 
the improvement had not been made. The very 
fact that market and shipping points are made 
more accessible to the farm makes the latter 
more valuable to the prospective purchaser. 
This point should need no argument to support 
it, and rests upon the same reasons which make 
a lot on an active business street in a city more 
valuable than a lot of equal size on a little-fre- 
quented side-street. The fact that more land can 
be cultivated, that more profitable crops can be 



58 KOADS, PATHS AND BEIDGES 

grown, that regular delivery of such perishable 
products as milk and cream, small fruits, truck 
products, etc., is made possible adds materially 
to the value of the land. If the owner sells after 
the improvement he reaps the benefit of the in- 
creased valuation. If he retains the land and 
cultivates it under this improved condition, his 
yield in income is greatly increased, to say 
nothing of his comfort and happiness. Exam- 
ples are numerous of farm products that have 
gone to waste because the expense of transport- 
ing them to market was greater than the amount 
which would be derived from their sale. Cen- 
sus statistics show that vegetables yield a re- 
turn per acre about six times as great as the 
cereals, while small fruits yield a return over 
eleven times as great as the cereals. Neither 
of these two products can be grown to advan- 
tage except near a good road over which they 
can be delivered regularly, quickly, and in good 
condition to the consumer. 

That the agricultural regions which are 
afflicted with bad roads are not utilising their 
resources as they should has been ascertained in 
numerous investigations. A striking example 



ROAD Lt]GISLATION 59 

of this was fonnd in an agricultural county sit- 
uated within easy reach of the cities of Wash- 
ington, Baltimore and Richmond. The roads 
of the county were almost impassable at certain 
seasons of the year, and as a consequence most 
of the agricultural land was untilled. An in- 
spection of the records of the local railway sta- 
tion at the principal town in the county revealed 
the fact that the incoming shipments of farm 
products such as could be produced within the 
county, exceeded the outgoing shipments by 
nearly 5,000 tons. In other words, the people 
of that particular county were actually buying 
from outsiders the food products which they 
should be producing and selling. 

A factor which should be considered in deal- 
ing with the subject of road improvement is the 
effect of such improvement upon population 
and the labour supply. The last census figures 
show that over 46 per cent, of our population 
live in cities of 2,500 inhabitants or more. The 
boys are leaving the farm for the more attrac- 
tive surroundings of the city. The immigrant, 
instead of settling in the country and thereby 
affording an adequate labour supply, is stay- 



60 EOADS, PATHS AND BEIDGES 

ing in the city, and by this unhealthy crowding 
is lowering the standard of living and of citizen- 
ship, and increasing the cost of living by in- 
creasing the ratio between the producer and the 
consumer of food. The rural sections which 
are improving their roads are not losing in 
population as are other sections. In an inspec- 
tion of the returns from the census of 1900 it 
was found that in 25 counties selected at ran- 
dom showing an average of only II/2 per cent, 
of improved roads, an actual decrease of 3,112 
persons to the county occurred between the 
years 1890 and 1900 ; while in 25 other counties 
having 40 per cent, of their roads improved, 
located in the same States, an increase of popu- 
lation took place in the same period averaging 
31,095 for each county. 

Better roads mean better schools, because the 
attendance is greater and the possibility for 
fewer buildings and more graded schools is 
increased. This point is manifested by inves- 
tigations made by the Government which show 
that in 5 States having a small percentage of 
improved roads, 59 out of each 100 of the pupils 
enrolled regularly attended the schools ; while in 




THE ROADS AND THE SCHOOLS. 



EOAD LEGISLATION 61 

5 States having a very high percentage of im- 
proved roads, the attendance was 78 out of each 
100 enrolled. In some prosperous communities 
having good roads the little one-room school- 
houses have been supplanted by six- and eight- 
room, graded schools, and a sufficient amount of 
money saved to provide conveyances for taking 
the children' to and from school. 

The benefits of road improvement are inca- 
pable of exact enumeration and definition, but 
they directly or indirectly affect the life of the 
rural dweller in every way. If he goes to 
church the condition of the road has its effect. 
If illness occurs in his family, the effect of the 
road is the relative quickness with which med- 
ical aid can be secured, and, in many cases, this 
also affects the cost of medical attention. The 
social intercourse with neighbours, and the 
pleasure of driving or automobiling depend 
upon the condition of the roads. All of these 
considerations must be taken into account when 
the question of road improvement is to be de- 
cided, and they must be weighed against the 
burdens incident to the improvement to be 
made. 



CHAPTER III 

LOCATIONS, SURVEYS, PLANS, 
SPECIFICATIONS 

Location. — A road should be so located as 
to permit the passage of traffic from one given 
point to another with the least possible ex- 
penditure of time and energy, but due consid- 
eration must be given to the initial outlay in 
the construction, and the subsequent outlay in 
the maintenance of the road, so that the total 
cost will not be greater than the resultant bene- 
fits. It must be apparent that many factors 
enter into the problem, frequently making it 
difficult for even the most skilled and thorough 
engineers to determine the right course to 
pursue. 

The economic considerations involved in 
road location are of two kinds: First, those 
relating to the accommodation of traffic; sec- 
ond, those relating to the road itself. The 
first deals with the utility of the road to the 

62 



LOCATIONS, SPECIFICATIONS 63 

community, while the second deals with the cost 
of construction and maintenance of the road. 
In the consideration of the traffic requirements, 
due weight should be given to the relative popu- 
lations dwelling along possible lines of loca- 
tion, the possibilities of development, agricul- 
tural and otherwise, following the location of 
the road, the necessity of shortening the dis- 
tance between given points and, lastly, the con- 
siderations of pleasure and recreation. The 
second consideration deals with the relative 
difference in cost among the various possible 
routes both for construction and maintenance, 
and involves not only the question of grades, 
and the availability of materials, but also the 
type of construction necessary. 

In general the most economic location of a 
road is that over which the annual cost of 
transportation, the annual cost of maintenance 
and the interest on the first cost of construction, 
together with the annual sinking fund, are 
lowest. Thus, it will be seen that the problem 
of road location is one dealing largely with 
financial considerations which must be given 



64 EOADS, PATHS AND BRIDGES 

precedence over considerations of an engineer- 
ing character. 

It is ordinarily held that the following prin- 
ciples should be observed in deciding on the 
final location of a road : 

1. Follow the route having the easiest grades. 

2. Select the shortest and most direct route 
commensurate with easy grades. 

3. Avoid all unnecessary ascents and de- 
scents. 

4. Cross ridges in lowest passes. 

5. Cross over or under railroads: a grade 
crossing means danger to every user of the 
road. 

6. Cross streams at most favourable sites, 
and as nearly at right angles as possible. 

7. Carry the balancing of cuts and fills only 
so far as it will reduce the cost of the total 
earth work to a minimum. When more earth 
is needed for a fill, it can readily be secured 
by slightly widening the cut, and where the 
cuts are in excess, convenient wastage can 
readily be found by widening the nearest fill. 

8. Do not overestimate the advantage of 
straightness. The curved road around a hill 



LOCATIONS, SPECIFICATIONS 65 

is often no longer tlian the straight road over 
it. In addition, a more or less sinuous course 
is an advantage from a maintenance stand- 
point, as on a winding road the wheel traffic 
has a tendency to spread over the entire sur- 
face, which is seldom the case on a straight 
road, particularly when the crown is high. 

9. Under modern conditions of traffic, sharp 
curves are a source of constant danger. The 
radii of curves should never be less than 100 
feet, and as low as this only where an unob- 
structed view can be had of the road ahead. 

10. Carry the road along the southern or 
western slope of ridges, if possible, so that it 
may be least exposed to storms and dry out 
more quickly after heavy rains and the melting 
of snow. 

Surveys. — The purpose of a survey is to se- 
cure the necessary data for determining the 
best location, as defined above, to supply such 
other data as may be needed in the prepara- 
tion of the plans and estimates of cost, and 
finally, together with the specifications, to 
serve as a guide in the actual construction of 
the road. The cost of the survey will vary 



66 ROADS, PATHS AND BRIDGES 

greatly with conditions. In tlie construction 
of an improved road through a new territory 
where the route is not clearly defined by natural 
topography, several surveys may be necessary, 
while if it involves the improvement of an al- 
ready existing road, the location of which can 
not be altered except to a very limited extent, 
a single survey may be sufficient. The more 
extensive surveys are usually divided into three 
parts : the reconnaissance, the preliminary, and 
the final survey. 

The reconnaissance is a more or less rapid exam- 
ination of the region to be traversed, for the purpose 
of obtaining information as to the general feasibility 
of the proposed route, and to secure the data neces- 
sary for the rapid and intelligent prosecution of more 
detailed surveys, should they prove necessary or ad- 
visable. Reconnaissance should, in general, include 
the examination of an area rather than of one or 
more routes. This is especially true where the road 
is of any considerable length, for, having familiarised 
himself with the entire area, the engineer will find no 
difficulty in choosing the one or more lines for which 
more detailed surveys are needed in order to deter- 
mine the final location. For this work the topo- 
graphical sheets of the United States Geological Sur- 
vey are extremely valuable, and if the region in ques- 



LOCATIONS, SPECIFICATIONS 67 

tion is covered by such a survey, a copy should, by 
all means, be secured. The topographical sheets, 
covering approximately an area 30 miles square, can 
be obtained from the Superintendent of Documents, 
for the sum of 5 cents each. Sometimes a study of the 
topographic map will make it possible to dispense with 
the field reconnaissance entirely, or at least reduce it 
to a minimum. 

In making the reconnaissance the following 
data should be carefully noted and recorded in 
the field book: The location and approximate 
elevation of all low passes; the general trend 
of all ridges and streams; the inclination of 
the rock strata; conditions as to dryness, etc. 
Advantageous bridge sites should be deter- 
mined; all sources of supply of road material, 
stone for concrete, water supply, etc., should 
be carefully noted. 

The reconnaissance should determine on one 
or more lines to be surveyed in detail in order 
to establish finally the best and most econom- 
ical route. For these lines an instrumental 
survey is necessary, or at least advisable. 
This survey should be accurate enough to mark 
the exact location of the proposed improve- 
ment on the ground, and also to obtain all neces- 



68 EOADS, PATHS AND BEIDGES 

sary data for plotting the map and preparing 
profiles, estimates of the earth work, etc. 

The survey usually consists of a transit line with 
levels and cross-sections taken at every station and 
at such intermediate points as may be necessary to 
give the required accuracy in computing the earth 
work. Full notes are also taken in regard to the 
width and character of all streams crossed, low and 
high water marks, all crossroads, private ways, the 
character of the soil and of any material suitable for 
road metal or use in constructing culverts or bridges 
which may be found in the neighbourhood. 

Plans. — The surveys should furnish all data 
for supplying drawings from which the esti- 
mates can be closely computed. The necessary 
drawings consist of a map or plan of the road 
and as much of the contiguous territory as may 
be desirable, a profile and a number of cross- 
sections. If bridges, culverts or retaining 
walls are necessary, fully detailed drawings 
must also be made for these structures. 

The survey-notes should be so complete that 
the map, cross-sections, and profile can be 
plotted rapidly and with sufficient accuracy. 
It is the poorest kind of policy to depend on 
the memory to supply lacking data. Every- 



LOCATIONS, SPECIFICATIONS 69 

thing should be taken in full in the field and 
entered in the notebook. 

The completed plans should be clear, con- 
cise and full of information. The profile 
especially should be a veritable encyclopaedia 
of information, both for the engineer and the 
contractor. It should show the present ground 
line, the finished grade, the depths of cuts and 
fills, the points of change of grade, location of 
all crossings and watercourses, together with 
elevation of high and low water levels, etc. 

The scale to which the drawings should be 
made will depend largely on the amount of de- 
tail to be shown. For most general purposes, 
a scale of 100 feet to the inch for the map and 
of 100 feet to the inch horizontally and 40 feet 
to the inch vertically for the profile will be 
found convenient. "Where much detail is to be 
shown, or on very difficult sections, this scale 
may be enlarged to any desired extent. 

The layman is apt to belittle the value of 
the preliminary work done on the surveys, and 
in making of plans, etc.; yet these are of the 
utmost importance and are absolutely neces- 
sary for an economical solution of the ques- 



70 EOADS, PATHS AND BEIDGES 

tions involved. A few extra days spent in this 
preliminary study of conditions will often re- 
sult in the saving of large sums of money, not 
only in the actual construction and in the 
maintenance of the road itself after it has been 
built, but in securing a much better route 
than one which might be secured without such 
study. Many of the questions involved in 
highway location are of an extremely difficult 
nature to solve, and it is needless to say that 
hard problems cannot, as a rule, be correctly 
solved without the requisite time and study. 

The following instructions for making road 
surveys are used by the Office of Public 
Eoads, United States Department of Agricul- 
ture: 

INSTRUCTIONS FOR MAKING ROAD SURVEYS 

All surveys for roads which it is proposed to im- 
prove with the cooperation of this Office should be 
made strictly in accordance with the following rules : 

All notes should indicate the date on which each 
part of the survey is made, the names of the men per- 
forming the work and the weather conditions. All of 
the work should be plotted and accompanied with a 
complete copy of the notes. 



LOCATIONS, SPECIFICATIONS 71 



TRANSIT AND LOCATION SURVEY. 

1. The transit line should be established following 
approximately the center of the road. At every 
hundred feet on this line temporary points are 
to be established. A spike driven into the road 
through a piece of red cloth or tape is a station 
mark that can be easily found after several 
weeks. - The measurement of this line is to be 
made either with a steel chain or tape, with a 
degree of accuracy of 1 in 3,000. 

2. "Wherever it is necessary to make a bend in the 
transit line, the transit instrument is to be set 
up at the bend, and the angle of the course 
ahead with that of the rear course measured, 
always measuring from the back sight around to 
the right. The angles are to be measured to the 
nearest minute, and where local disturbances do 
not preclude doing so, magnetic bearings of each 
course should be observed. 

3. Opposite the points established in the road, and 
on the side far enough removed to be clear of 
all construction work, stakes are to be driven. 
These stakes should be about 24 inches long, and 
driven for a depth of 12 to 15 inches. The 
stakes are to be numbered, beginning with zero, 
each hundred feet to be a unit. The offset dis- 
tance of centre of stake from the station point 
on the transit line is to be measured and recorded 
in the notes to the nearest 0.10 foot. 

4. At all bends stakes should be set on both sides 



72 EOADS, PATHS AND BRIDGES 

of the road in a line through the point of de- 
flection and at right angles with the back course. 
These stakes will be used as reference stakes and 
should have a small nail driven in the top from 
which measurements to the nearest 0.01 foot are 
to be taken to the deflection point in the transit 
line. Reference stakes should be driven flush 
with the ground and another stake driven near 
by for a marker. 

5. As a rule, deflection points should be made at 
even stations or half stations, a half station 
being designated by the number of the previous 
station with + 50. 

6. After the location of the transit line as described, 
offset measurements are to be taken at each sta- 
tion or as much oftener as may be necessary to 
locate properly the sides of the travelled way and 
fences or walls alongside the road wherever such 
exist. 

7. Measurements should be taken so as to locate all 
bridges, culverts and cross drains of whatever 
description, and the direction of flow through 
them should be shown by an arrow. The clear 
opening of all waterways should also be indi- 
cated. 

8. The location of all crossroads and private en- 
trances should be indicated. 

9. Landowners' names should be obtained and di- 
viding fences, where such exist, should be located. 



LOCATIONS, SPECIFICATIONS 73 

LEVELS. 

After the transit and location survey is made the 
levels are run as follows : 

10. Permanent bench marks at either end of the 
work and at convenient intermediate points are 
to be established well out of the way of any con- 
struction. The number of bench marks should 
be at 'least four or five to the mile and as much 
oftener as convenience may require. Bench 
marks should be on permanent objects on which 
a rod can be conveniently held, and located 
where they can be readily identified on the 
ground. The roots of trees with low-hanging 
limbs are not convenient, nor is a point so far 
back from a line of trees along a road as to shut 
off all view of the bench mark, except directly 
opposite it. 

11. A line of check levels should be run touching 
every bench mark, and separate notes kept of 
these check levels. Elevations should check to 
0.10 foot per mile. All readings on bench marks 
and turning points should be to nearest 0.01 
foot. 

12. Eeadings for ground elevations should be to 
nearest 0.10 foot. Ground elevations are to 
be taken at the centre of the road at each station 
or 100 feet and as much oftener as may be neces- 
sary to show irregularities in the profile or cross- 
section. 

13. At each place where a centre reading is taken 



74 EOADS, PATHS AND BEIDGES 

side readings are to be taken to show accurately; 
the cross-section of the road. 

14. To take a cross-section, first take reading of the 
rod on the top of the stake at that particular 
station and a ground reading at same point. 
Enough readings are to be taken at other points 
across the line of the road to show the true shape 
of the banks, gutters and ditches on each side 
and the road between. The distance of each 
reading from the transit line is to be recorded 
as well as the reading itself. 

15. Elevations are to be taken of the following 
points : 

a. The bottom of openings at each end of 
all culverts, indicating them as east and west or 
north and south ends. 

b. Bridge floors, tops of abutments and bridge 
seats. 

c. The entrance and exit ditches on stream 
bottoms about 25 feet from either end of a cul- 
vert or bridge, so as to give the grade of the 
stream bed near the culvert. 

d. High and low water in streams (estimated). 

e. "Water surface of streams as found. 

Plan Scale— r' = 40' 

Profile Vertical Scale — 1'' == 4' 

Horizontal Scale— 1'' = 40' 

Cross-sections Scale — 1" = 4' 

Note. — A profile of road with a grade of more than 
4 per cent, should be plotted with a vertical scale 
of 1" = 8'. 



LOCATIONS, SPECIFICATIONS 75 

Specifications, — The purpose of a set of 
specifications is to set forth in clear and un- 
mistakable language the work to be done, the 
manner of doing it, and the character of the 
materials to be furnished. Usually the spec- 
ifications, together with the engineer's esti- 
mate, form the basis on which the contractors 
bid, and after the contract has been let, the 
specifications serve as a guide for both con- 
tractor and engineer in the further prosecution 
of the work. In how much detail the various 
operations are to be specified will depend upon 
conditions. Sometimes it may be advisable 
simply to set forth certain standards to which 
the finished work shall conform. In this event, 
the manner of carrying on the work is left en- 
tirely with the contractor. When there are 
unknown or hazardous conditions, such as are 
sometimes met with in the construction of 
foundations for bridges, or erecting bridges 
over streams subject to violent floods which 
may endanger the work in progress, it 
may at times be considered preferable to 
let the contractor assume the risk. In this 
case, however, great care should be taken to 



76 EOADS, PATHS AND BEIDGES 

secure a contractor of known integrity and re- 
sponsibility. 

More often, however, not only the standard 
to which the finished work is to comply, but 
also the character of the materials which are to 
enter into the construction, as well as the man- 
ner in which the work is to be carried on, are 
prescribed. Oftentimes the specifications are 
made so complete as to form a perfect formula 
for the contractor to follow. It should be kept 
in mind, however, that under such conditions, 
if for any reason the finished work does not 
comply with the requirements, the contractor 
cannot be held legally responsible so long as 
he has substantially complied with the various 
specifications. The courts have ruled that a 
man cannot be held responsible for the results 
of his work when he is not given any choice in 
the manner in which it must be done, but must 
follow regulations in every detail. 

The specifications when drawn should be ex- 
amined, first as a whole, and then each clause 
separately. No conflicts or ambiguities must 
exist, and nothing should be inserted which is 
not necessary. It is a good rule to specify only 



LOCATIONS, SPECIFICATIONS 77 

what is really wanted, and to write these speci- 
fications so clearly that there can be no mis- 
take as to what is desired. One clause which 
is nearly always found in all specifications 
for road building involving any considerable 
amount of excavation, and which has in the past 
caused more friction than almost any other 
single clause, is that pertaining to the classifi- 
cation of the earth work. Quite often three 
classifications are given, as earth, loose rock, 
and solid rock, and sometimes a fourth is 
added — that of hard pan. These classifica- 
tions are in themselves all well and good, but 
the difficulty comes in describing the different 
classifications in such a manner that in the 
field one class may be readily distinguished 
from the next. Because of this difficulty it 
would seem advisable in road work to limit the 
classification of earth work as much as possi- 
ble. The drawing up of proper specifications 
is no small part of the work of the engineer, 
and the manner in which they are drawn will 
often not only save endless friction and hard 
feelings during the progress of the work, but 
save much money to the community. They 



78 EOADS, PATHS AND BEIDGES 

may seem simple at first glance, but tlie writing 
of proper specifications requires knowledge, 
skill, experience and ability. 



CHAPTER IV 

THE EARTH ROAD 

AccoEDii^G to a careful mileage census made 
by the U. S. Office of Public Roads, there were 
in 1909 about 2,210,000 miles of road in the 
United States, of which upwards of 2,000,000 
miles may be classed as earth roads. It is 
evident from this showing that the task of sur- 
facing all of our roads with hard material, or 
even the major portion of them, is so great as 
to be impossible of accomplishment for a great 
many years to come. The best that we can do 
is to classify the roads so that only those which 
carry the heaviest traffic will be surfaced with 
hard material, while the remainder will be 
given such simple and efficient treatment as to 
render them capable of meeting requirements 
at small outlay. 

Already an enormous traffic is carried over the 
country roads in the United States, estimated at not 

79 



80 EOADS, PATHS AND BEIDGES 

less than 250,000,000 tons annually. Impressive as 
this tonnage appears, it is but a fraction of the traffic 
which our country roads would be called upon to sus- 
tain if they were in fairly good condition. Proof of 
this is found in the experience of France, where an 
official census has brought out the fact that the public 
roads carry one and one-third times as much freight 
as the railroads. According to the reports of the In- 
terstate Commerce Commission, the railroads of this 
country carry upwards of 900,000,000 tons annually. 
If our public roads were used to the same extent as 
the French roads, it would mean a traffic of about 
1,200,000,000 tons annually instead of the 250,000,000 
tons, as at present. 

An earth road may be defined as a road com- 
posed of natural soil, to whicli no other kind 
of surfacing material has been applied, and 
with which no binder or filler has been mixed. 
It differs from a sand-clay road to the extent 
that the latter is composed of sand and clay 
mixed in suitable proportions. 

Location, — It is important that the road be 
located so as to serve the needs of traffic best, 
to permit due economy in construction and 
maintenance, to obtain a grade as nearly level 
as practicable, and to permit thorough drain- 
age. The considerations which should govern 



THE EAETH EOAD 81 

the location of roads are fully dealt witli in 
Chapter III. By far the greater proportion 
of our roads have been located at haphazard, 
in many cases following Indian trails, paths 
of wild animals and farm boundaries. This is 
particularly true in the Eastern States, which 
were settled first. The result is that instead 




T5p CK^URTACe O/TCV. 



*Si/e<5Qa. •6iifEDR°JN. 



Tincm. \5£cnoN Fm S/De-Zf/u. aud Qmuum.' Slope LoofTiajts. 

of the roads being adapted to the traffic require- 
ments, the traffic is compelled to adapt itself to 
the road. In the West the roads are laid out 
on section lines. These sections are all square, 
and consequently the roads are all at right 
angles. If a person desires to cross the coun- 
try, it is necessary for him to follow the 
boundaries of a series of rectangles, instead 
of going directly to the point he desires to 
reach. If it were possible to relocate the pub- 
lic roads according to the needs of traffic and 



82 KOADS, PATHS AND BEIDGES 

agricultural development, so that distances 
might be shortened and easier grades obtained, 
our total mileage could be cut down at least 
100,000 miles, and communication rendered far 
less difficult and costly in every section of the 
country. Such general relocation is impossi- 
ble, and the best that can be done is to avoid 
unwise location of new roads, and to relocate 
old roads whenever conditions require and per- 
mit. 

Grades, — The term '^ grade,'' as used in this 
chapter, means the slope of the road along its 
length. A steep road would be described as 
a road having a steep grade. Among road 
builders the grade is expressed in terms of 
percentage, as 1 per cent., 5 per cent., 10 per 
cent. ; each per cent, meaning a rise of 1 foot in 
each 100 feet of length. 

In the construction of new roads and the re- 
grading of old roads it is customary to specify 
a certain per cent, as the maximum grade al- 
lowable at any point on the road. A minimum 
grade means the least that can be allowed for 
good drainage. A number of considerations 
are influential in determining the maximum 



THE EAETH EOAD 83 

grade whicli may be allowed, but the most im- 
portant is expense, as it is necessary to adapt 
the work in hand to the means available. The 
topography of the country has an important 
bearing on the question of grades, as a much 
more nearly level road can be specified in a 
flat or rolling country than in a mountainous 
region. The character of the soil also has 
some bearing upon the question. By common 
consent it is agreed among highway engineers 
that no road should exceed a grade of 5 per cent, 
except in extreme cases where, by reason of 
natural difficulties or lack of funds, it is im- 
practicable to reduce the grades to that point. 
Steep grades are a powerful handicap to 
traffic, and wherever possible they should be 
eliminated. While it is a matter of common ob- 
servation that the load which a team of horses 
can draw on a steep hill is very much smaller 
than the usual load on level ground, it is not 
generally known that on an average macadam 
road it requires approximately four times as 
much power to draw a load up a 10 per cent, 
grade as is required to draw the same load on a 
level. This means that an eight-horse team 



84 EOADS, PATHS AND BEIDGES 

would be required to draw up a 10 per cent, 
hill the same load that two horses could draw 
on a level road. It may be said, in modification 
of this, however, that for short distances a horse 
is able to exert about twice his natural pull, so 
that if the grade were short, four horses might, 
by exerting their maximum pull, accomplish the 
same result. But the loss of tractive power on 
steep grades is greater than shown by theory, 
since the power of a horse decreases very rap- 
idly on steep inclines. The leading authorities 
on highway engineering express the matter 
about as follows: Assuming 1,400 lbs. to be 
the load which one horse can draw on a level 
earth road, he should be able to draw 650 lbs. 
on a 5 per cent, grade and 340 lbs. on a 10 
per cent, grade, with about the same degree of 
ease. 

While it is frequently expensive to obtain 
easy grades, the fact should be borne in mind 
that the work is permanent in character. No 
matter what surface material may be applied to 
a road, it will wear out and have to be replaced. 
Not so with the grade; it is a permanent step, 
not only toward the building of a good earth 




I 




^ 




- _... — 





TRANSFORMATION OP' AN EARTH ROAD. 

1. (Top.) Preseiit condition, improved by drainage and a macadam 
surface. 2. Past condition, sunken and water-soaked. 



THE EAETH EOAD 85 

road, but also toward any type of improved 
road which may be determined upon at some 
later time. A steep road is much more difficult 
to maintain than a road with a flatter slope, as 
the former is much more likely to be damaged 
by the action of water, which tends to wash and 
gully the surface. The injurious action of 
horses' hoofs and narrow-tired, heavily loaded 
wagons is also more pronounced on steep 
grades. 

There are three ways by which an easy 
grade may be obtained: First, to locate the 
road so that it will go round the hill, instead of 
over it; second, to have it run diagonally up 
the face of the hill, doubling back and forth a 
sufficient number of times to keep the grade 
down to the desired per cent.; third, to cut 
down the hill. 

Another plan, which might be considered a modifi- 
cation of the second, is to begin the ascent of the hill 
quite a distance from the base. It is a matter of 
common observation that many country roads run 
straight to the base of a hill before beginning the 
ascent. In almost every case they could, by leaving 
a straight line some distance back, approach the hill 
on an easy grade. The question of cost will largely 



86 EOADS, PATHS AND BEIDGES 

determine which of these three methods should be 
adopted. If the hill is a long one, it will usually 
be found cheaper and more practicable to go around 
it. This will not necessarily result in lengthening the 
road, as shown by the familiar example of the bucket 
bail, which is the same length when resting on the 
rim of the bucket as when in a vertical position. If 
the hill is short, it will probably be cheaper and more 
satisfactory to cut it down, using the material from 
the cut to fill in the approaches on each side. Where 
the road leads from lower ground to a plateau, the 
method of carrying a road up the face of the hill 
diagonally will sometimes be found most feasible, but 
each case must be decided in conformity with the 
local topography. 

If it is necessary to lengthen the road to even 
a considerable extent in order to secure easy 
grades, it may be found in many cases to be 
real economy to do so. The same energy which 
would be expended by a horse in drawing the 
load up a steep grade would suffice to draw it a 
far greater distance on a comparatively level 
road. Many scientific tests have been made to 
demonstrate this in exact terms. The point 
will be made sufficiently clear, however, by the 
statement that to lift a ton a distance of one 
foot requires an expenditure of energy amount- 



THE EAETH EOAD 87 

ing to 2,000 foot-pounds. Therefore, in draw- 
ing a ton a distance of 100 feet on a 10% grade, 
the load would have to be lifted ten feet, in- 
volving an expenditure of 20,000 foot-pounds of 
energy, and all this is in addition to the force 
required to draw the load a distance of 100 feet 
on a level. It must, therefore, appear that the 
burden imposed by distance is not nearly as 
great as that imposed by steep grades. Of 
course it should be borne in mind that a mate- 
rial lengthening of the road may add to the 
cost of construction and the cost of mainte- 
nance. The best course is to give due weight 
to all factors in the problem. 

Drainage, — Water is destructive to all roads, 
and particularly to earth roads, so much so 
that good drainage is the keynote of success in 
road construction. To remove quickly the 
water which reaches the surface of the road, 
and to intercept the flow of water from higher 
grounds toward the road, a system of surface 
drainage must be provided. Water attacks the 
foundation of the road as well as the surface, 
in many cases, and to meet this danger sub- 
drainage must be provided. The subject of 



88 EOADS, PATHS AND BEIDGES 

drainage is, therefore, subdivided into surface 
drainage and subdrainage. 

Surface Drainage, — Most country roads are 
too flat to sbed water; in fact, many of them 
are concave, owing to the fact that traffic is kept 
consistently in the centre and wears down the 
surface until the road is more in the nature of 
a ditch than a highway. As the roads are usu- 
ally repaired only once or twice a year, grass 
and weeds are permitted to grow close up to 
the travelled way, still further preventing the 
flow of water from the road to the ditches. 

If the road is comparatively level, so that the 
water stands upon it, the surface soon becomes 
soft, causing deep holes and ruts to form under 
the impact of traffic. When this incipient 
damage is done, every heavy rain thereafter 
hastens the destruction of the road, because the 
water follows the wheel ruts, widening and 
deepening them. Eventually, if preventive 
measures are not taken, this will totally de- 
stroy the road. In any event, under such con- 
ditions the cost of repair will be large. 

This damage to the surface can be easily 
prevented by giving the road a crown or slope 



THE EAKTH EOAD 89 

from the centre to the sides sufficient to cause 
the water to drain quickly to the side ditches, 
instead of running down the middle of the road ; 
but it is necessary to exercise judgment in 
determining upon the slope or crown to be 
adopted. If the crown is made too steep, the 
water will rush off to the side so quickly as to 
cause damage to the shoulders or sides of the 
road. If it is too slight, the water will flow 
down the centre instead of to the sides. In a 
perfectly flat country a somewhat slighter 
crown is necessary than on the hillsides, be- 
cause in the former case there is no tendency 
of the water to flow down the centre, while in 
the latter case the slope at the sides must be 
at least equal to the longitudinal slope. Other- 
wise, the water will follow a diagonal course 
and may carry otf some of the surface material. 
The best practice is to allow a slope, averaging 
from % inch to 1 inch to the foot, but the indi- 
vidual judgment is necessary to determine 
whether it is advisable in specific cases to in- 
crease or decrease these standards slightly. 
The road builder should avoid the mistake of 
crowning his roads too steeply, not only because 



90 EOADS, PATHS AND BEIDGES 

of the consequent damage to the shoulders, al- 
ready referred to, but because in such cases the 
wagons will ^^ track" or keep to the centre and 
eventually cause the road to be flat or hollowed 
out on the most heavily travelled portion. 

A natural mistake is sometimes made by 
reason of the literal following of text-books in 
giving a uniform slope from the centre to the 
sides, which results in making the road like a 
roof, in which the centre of the road forms the 
comb. In actual practice the road should be 
curved and the total slope from centre to sides 
should be such as to give the required average 
slope per foot. By actual measurement it might 
appear that the slope will be only % of an inch 
to the foot near the centre and considerably 
more than an inch to the foot at the side of the 
road. This is all right, as long as the road 
maintains its convex shape. On sharp hillside 
curves it is usually advisable to give a single 
inward slope to the road. 

Ditches. — The next most important point in 
providing for surface drainage is to construct 
suitable side ditches. All these side ditches 
should have a fall or slope of at least six inches 



THE EAETH EOAD 91 

in eacli 100 feet in length ; if the fall is less, the 
water will not flow quickly enough and trouble 
will be had, particularly in winter or early in 
the spring when the snow melts. These side 
ditches must be ample in size to provide for 
the greatest volume of water that may reason- 
ably be expected by reason of heavy rains, 
storms or the melting of snows. In order to 
provide sufficient capacity, the ditches should 
be made wide, rather than deep, as deep ditches 
beside a road are dangerous to traffic and are 
more expensive to construct and maintain. 
The best plan is to have frequent outlets from 
the ditches, either by means of culverts, pipes, 
or by turning the ditches into lower ground, 
rather than to allow the water to flow along the 
road any great distance. 

Five 12-inch pipes in a mile of roadway are about 
as cheap and far more effective than one 24-inch pipe, 
because the water is disposed of before it gains force 
or headway or has time to damage the road. The 
maximum velocity for a 24-inch vitrified tile, flowing 
full without head on a grade of 1-inch per 100 feet, is 
3.6 feet per second, or about 2i/2 miles per hour; 
when the grade or slope is increased to 36 inches in 
a distance of 100 feet, the velocity becomes 20 feet 



92 KOADS, PATHS AND BEIDGES 

per second, or about 13% miles per hour. The dis- 
charge for the 24-inch pipe in the first instance, will 
be 5,086 gallons per minute, while in the second in- 
stance it will be 28,260 gallons per minute. It will, 
therefore, be seen that a 24-inch pipe, laid on a grade 
of 36 inches to the 100 feet, will have over five times 
the capacity of the same pipe laid on a grade of 1 
inch to the 100 feet. 

Under the same conditions, the maximum velocity 
for a 12-inch tile on a grade of 1 inch per 100 feet, 
equals 1^/4 feet per second, or about % of a mile per 
hour, and for the same tile on a grade of 36 inches to 
the 100 feet, the velocity would be 7% feet per second, 
or about 5% miles per hour. The discharge for the 
12-inch tile in the first instance would be 442 gallons 
per minute, and in the second instance 2,650 gal- 
lons per minute, or about five times as much. It will 
thus be seen that comparing the 12-inch pipe and 
the 24-inch pipe on a grade of 36 inches to the 100 
feet, the five 12-inch pipes would remove in the aggre- 
gate 13,250 gallons per minute, as compared with 
28,260 gallons per minute by the one 24-inch pipe, 
but the advantage of the former lies in the fact that 
the water is removed at five points instead of one. 

Another important point in the foregoing is, 
that by increasing the grade or slope of the 
pipe, the capacity for removing the surface 
water is enormously increased. In order to 
protect culverts or pipes from damage, when 




AX EARTH ROAD WITH PROPER CROWX. 







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P.i'ii 



AN UXDRAIXED PRAIRIE ROAD IN SPRING. 



THE EARTH EOAD 93 

discharging water under full pressure, or when 
a culvert or pipe is given a considerable slope 
or grade, it is desirable that the joints be 
cemented, if a pipe is used, and that the ends 
of the culverts be protected with masonry, or 
concrete wing walls. In addition to this the 
spillway should be paved with cobblestones, in 
order to prevent washing. Another point in 
favour of having a sufficient fall or slope to the 
culverts is that they will be self -cleansing and 
so keep open. A culvert laid flat may soon fill 
up. 

Mud-holes cannot be successfully drained, as 
a rule, with culvert pipes. The best plan is to 
throw out the soft mud and replace it with good 
firm earth, so that it becomes level after con- 
solidation with the surrounding surface. The 
ditches should then be sufficient to drain the 
mud-holes and carry the water to the culverts. 

The sides of these ditches should have an 
easy slope, particularly on the side of the road, 
as this will tend to prevent accidents to traffic, 
as well as the caving in of the banks of the 
ditches. The construction of deep ditches 
should be avoided. In most cases ditches made 



94 EOADS, PATHS AND BRIDGES 

with the road machine in shaping up the surface 
of the road is sufficient for surface drainage. 

Culverts should be built at the low points 
where outlets are available and existing streams 
should always be utilised for outlets, when pos- 
sible. Where only a slight volume of water 
is to be removed from ditches, it may be carried 
under the road in tile pipes instead of concrete 
culverts. In such cases the pipes should be 
laid deep enough to prevent their being broken 
by the traffic. If it is impossible to place the 
pipes deep enough to be removed from the 
effect of traffic, it is well to use concrete. The 
construction of small culverts and drains will 
be more fully explained in a separate chapter. 

Subdrainage. — Many thousand miles of pub- 
lic road in the United States are located on low, 
swampy ground, or on ground which possesses 
very poor natural drainage. A large percent- 
age of prairie roads are in bad condition for 
several months each year, by reason of a wet 
subsoil. In such cases surface drainage, no 
matter how effective, will not always serve to 
keep the road in good condition. Conse- 
quently, it becomes necessary at times to install 



THE EAETH EOAD 95 

a system of "anderdrainage, so as to clear tlie 
soil of surplus water and to give the road a 
solid, dry foundation. Water in the subsoil 
becomes ice in winter and expands, thereby 
heaving the road. In the spring the ice melts 
and the foundation becomes softened to such 
an extent that the whole road gives way, or, 
as it is generally stated, *Hhe bottom drops 
out of the road.'' It can readily be seen that 
the maintenance of roads under these condi- 
tions is exceedingly difficult and very expensive. 
Underdrains can usually be provided at small 
expense and will last quite a long time, if prop- 
erly maintained. Many roads are greatly dam- 
aged by springs in the soil. These should be 
tapped by blind drains of stone or pipe, and 
the water carried diagonally to the side ditches. 
Hillside roads are often subjected to the de- 
structive action of water, which drains from 
the higher ground into the foundation of the 
road. Surface drainage is, in some cases, suf- 
ficient to protect the road. Where it is not 
sufficient, the best plan is to dig a deep ditch 
some distance above the road on the hillside, 
of sufficient capacity to intercept and carry off 



96 EOADS, PATHS AND BEIDGES 

tlie flow of surface water. This ditch should 
be given outlets to lower ground at frequent 
intervals. 

The usual method of underdraining a road 
is to provide a narrow trench on each side at 
the bottom of which a pipe of from 4 to 6 inches 
in diameter is placed. Ordinarily a 4-inch 
pipe will be found sufficient. These pipes are 
usually composed of terra cotta tile. The 
depth to which these pipes should be laid de- 
pends largely upon the character of the soil and 
the depth of the frost line, but in general it 
should be about 3 or 4 feet. The pipe should 
be laid near the bottom and the trench then 
filled with broken stone, gravel or broken brick- 
bats. The pipe should have a fall of not less 
than 6 inches for each 100 feet of length. It 
is unwise to give too much fall to small drain 
pipes, as the swift current may wash away the 
ground about the drains and displace them. 
The sides of the trenches should slope gradu- 
ally, as this will prevent the ground from cav- 
ing in and will also give greater stability to the 
drain pipes. The outlets or spills for the pipes 
should be paved so as to prevent washing. 



THE EAETH EOAD 97 

Care should be taken to lay the tile true to 
grade as, otherwise, it will soon become in- 
effective. Wherever the pipe sags it will soon 
be filled with sediment, and if there is a crest 
the silt will accumulate immediately behind it. 
The ends of the pipes should be covered with 
an iron grating, which will prevent vermin from 
entering. 

Where pipe drains or concrete culverts can 
not be provided, it is sometimes practicable to 
construct blind drains with flat stones. 

Some authorities recommend a line of tile 
under the centre of the road, but this is not prac- 
ticable as a rule, as it is much more expensive, 
and involves a greater amount of digging, both 
in the original installation of the pipe and in re- 
pairs, should they become necessary. Further- 
more, if the road is later on surfaced with hard 
material, it will become increasingly expensive 
to reach the pipe for repairs. 

A method which may be practised to advan- 
tage in soil which is free from rock and easily 
worked, and where the ground is practically 
level is to grade the road up in the form of an 
embankment above the level of the surround- 



98 EOADS, PATHS AND BRIDGES 

ing country. The water may then drain from 
the road instead of to it. 

Width of Road. — The width of right of way 
is specified in most of the States by statute, but 
is usually not less than 40 and not more than 
66 feet. The width of the travelled roadway is 
much less, as allowance of at least six feet on 
the outside of each ditch should be made for 
footways. It is advisable to have the road 
wide enough to meet all traffic requirement, but 
it is a mistake to have the travelled way ex- 
ceptionally wide, as this will necessitate deeper 
ditches, and will not only be more costly to con- 
struct but also to maintain. 

Clearing Roadway. — ^After determining the 
width of roadway, ditches and footways, the 
next step is to remove all stumps, brush, roots, 
rocks, etc. 

Cuts and Fills. — The practical road builder 
always endeavours to establish the grade of the 
road so as to make the cuts and fills equal, as 
otherwise waste of material will result. If the 
cuts are greater than the fills, the result will be 
a greater amount of loose earth than can be 
used, while if the fills are greater, it will be nee- 



THE EARTH EOAD 99 

essary to obtain additional earth from borrow- 
pits and haul it to the road. Some of the cuts 
and fills are so far apart that it is cheaper to 
obtain material from the side of the road, or 
to waste the material from the cuts, rather than 
endeavour to balance the cuts and fills. 

An important point to be considered in connexion 
with excavation is that loose earth at first occupies 
greater space than compact earth, while the final re- 
sult is that there is considerable shrinkage in fills. 
It is a curious fact that the earth in a fill or embank- 
ment actually compacts to less space than it occupied 
in its original position. The amount of shrinkage 
varies with the character of the soil and is about as 
follows : Gravel or sand, 8 per cent. ; clay, 10 per 
cent. ; loam, 12 per cent. ; loose surface soil, 15 per 
cent. ; and puddled clay, 25 per cent. 

The side slopes on cuts and fills must be 
given an angle which will insure stability and 
at the same time cause the least waste of mate- 
rial. The method of determining the angle of 
the slope is by the ratio of the horizontal dis- 
tance to the vertical distance. We can assume 
the side of the embankment to form the hy- 
pothenuse of a right-angled triangle. If the 
vertical line of the triangle is 1 foot and the 



100 EOADS, PATHS AND BRIDGES 

base line extending out to the point of the slope 
is 1% feet, the slope should be designated as 
1% to 1. The slope will, of course, vary with 
the nature of the soil. Common earth will 
stand a slope of 1 to 1, but it is safer to make it 
1% to 1. Gravel requires a slope of 1% to 1, 
while clays vary widely, ranging from 1 to 1 to 
a slope as flat as 6 to 1. In general practice 
the slope of 1% to 1 is found best. It is well 
to sow grass seed on slopes, or, if that is not 
practicable, to sod them, as greater stability 
will be obtained in this way. 

For slight cuts and fills, where the soil will permit, 
it will be found that the road machine or road grader 
is sufficient; where the soil is hard or mixed with 
pebbles or field stone, it is frequently found to be 
economy to use a road plough and follow it with the 
road grader. For excavation on a larger grade 
the slip scraper is exceedingly useful, and where the 
cuts and fills are considerably apart the wheel scraper 
will be found most useful. The wheelbarrow is 
rarely used, except for small jobs or in wet, swampy 
places. The elevating grader is frequently used to 
advantage in prairie regions and in low, flat ground 
free from rocks, as it elevates the road above the 
surrounding country, and thereby promotes good 
drainage. It can also be used to advantage in load- 



THE EAETH KOAD 101 

ing wagons on cut-and-fill work. Road-building 
equipment and its use are taken up in detail in a 
separate section of this chapter. 

When the roadway has been cleared and 
brought to a desired grade, careful examina- 
tion should be made of the surface at all points, 
and wherever it is found to be soft, spongy, 
or insecure, the soft material should be re- 
moved and replaced with good, firm earth, 
sand or gravel. The material should then be 
tamped in place until the surface is smooth and 
compact. 

Road Implements and Machinery and Their 
Use, — Eoad building has been much simplified 
and cheapened by the substitution of machinery 
for hand labour in transporting material from 
place to place. The first advance over the bur- 
den bearer was the wheelbarrow. An Ameri- 
can engineer in the Philippine Islands tells 
of his experience with the native labourer when 
the wheelbarrow was introduced there as part 
of the regular road-building equipment. As 
soon as the barrow was loaded two of the 
natives bravely picked it up, carried it to the 
point where the material was needed, emptied 



102 EOADS, PATHS AND BEIDGES 

it and carried it back; the wheel at the end of 
the barrow had no significance to them. Mod- 
ern practice has made even greater strides 
to-day. The wheelbarrow is rarely nsed now, 
except for small jobs or in wet and swampy 
places. It has been superseded by some form 
of drag scraper drawn by horses. 

The complete road-building outfit consists of 
a great number of units, which may be roughly 
enumerated as ploughs, drag and wheel scrap- 
ers, road graders or road machines, disc har- 
rows, dump carts, elevating graders, sprinklers, 
rollers, crushers with elevators, screens and 
bins ; and in the construction of roads of modern 
type with bituminous binders a great deal of 
special equipment has been devised such as tar 
and asphalt spraying machines, and tank-wagon. 

Scrapers are intended for use in moving 
material after it has been loosened by plough- 
ing. They are of two kinds — drag scrapers and 
wheel scrapers. The drag scraper is made in 
several sizes running from about 3 cubic feet 
capacity to a capacity of from 5 to 7 cubic feet. 
The average cost is from $6 to $7 each. The 
smaller size is designed for one horse and the 



THE EAETH EOAD 103 

larger sizes for two horses. The drag scraper 
is used for moving earth short distances. 

The wheel scraper may be described as a 
steel box on wheels, open in front, and provided 
with levers by which the box may be raised and 
lowered and its contents dumped. The capac- 
ity is usually from 9 to 16 cubic feet. The cost 
should be from $25 to $40. 

The elevating grader is provided with a 
frame, resting upon four wheels, from which is 
suspended a plough and frame carrying a wide 
travelling belt. The plough loosens the earth 
and casts it upon the inclined belt, which in 
turn carries it to the embankment, or to the 
wagons, as the case may be. This machine is 
particularly adapted for the construction of 
earth roads in a prairie country. It cannot be 
used to advantage in a very hilly or rocky 
country. 

The disc harrow is used mainly in the con- 
struction of sand-clay roads for the purpose 
of thoroughly mixing the sand and clay. Its 
use will be explained in the chapter on sand- 
clay roads. 

The steam roller, the sprinkler and the 



104 EOADS, PATHS AND BRIDGES 

crusher, with its appliances, are mainly used in 
the construction of gravel and crushed-stone 
roads. It will be described in greater detail 
in the appropriate chapters. 

For use about the farm and in the treatment 
of ordinary earth roads, the plough, the drag 
scraper, the wheel scraper and the road ma- 
chine are the implements most generally used. 
A split-log drag is very simple and exceedingly 
useful in the maintenance of earth roads. It 
will be described in another chapter. 

Under certain conditions the plough is a 
most useful implement in road work. When 
the soil on the surface of a road is excessively 
sandy and the subsoil is of clay, or of gravel 
and clay, the road will be greatly benefited by 
a deep ploughing. The ploughing brings the 
clay from beneath and mixes it with the surface 
soil and sand. Thus a sand-clay road is 
formed at small expense. On the other hand, 
if the road is entirely formed of deep sand, it 
will prove a very great mistake to plough up 
the road bed unless clay can be added. The 
ploughing only deepens the sand and breaks 
up what little hard surfacing material has been 



THE EAETH EOAD 105 

formed on top. Again, if the surface has only. 
a little sand or gravel in it, and the subsoil is 
practically pure clay, it will prove a great mis- 
take to plough it up. To do so would bring an 
excess of clay to the surface, and effectually 
destroy the surface coating of sand or gravel 
or soil. These are apparently very small and 
insignificaiLt matters, yet a correct understand- 
ing of them, with regard to the principles in- 
volved, will enable a road foreman to improve 
the roads under his charge. 

When ploughing is undertaken, the best 
method is to begin in the middle and ^* back- 
furrow'' both ways to the middle, thus forming 
a crown. After the road has been ploughed, 
it may be harrowed and carefully smoothed. 
Ploughing should be done in the spring or early 
summer. A plough can be used in ditches to 
advantage. In excavating there is no better 
way to loosen earth than by the use of the 
plough. For this purpose there are various 
kinds in use. The old-fashioned coulter plough 
is effective in breaking up hard gravel or other 
material. 

When it is necessary to make ditches wide 



106 EOADS, PATHS AND BEIDGES 

and deep, nothing has yet been devised better 
than the ordinary drag scraper. It is service- 
able in hauls under seventy-five feet long for 
making fills. Frequently a road becomes worn 
down and requires widening. The sides may 
be ploughed and the earth pulled in with the 
scraper. When both sides have to be pulled 
in, it is a good plan to make a circular trip, 
pulling in the earth from both sides at the same 
time. Ditch work may often be handled in this 
way and greatly facilitated. Two horses and 
two men will handle many times more earth 
than could be handled if work was done by hand 
with shovels. It is a mistake, however, to at- 
tempt to handle material in long hauls with a 
drag scraper. The wheel scraper is better 
adapted to such hauling, but still should be lim- 
ited to about 1,000 feet haul. Furthermore, the 
wheel scraper is not well adapted to ditch work, 
for the reason that the wheels require a greater 
width than is usual in ditches. These scrapers 
are better adapted to grading and handling 
earth where many cuts and fills are necessary. 
As a rule, it does not pay to work less than 



THE EAETH EOAD 107 

four to six in a run, because an extra team is 
necessary to help in loading, and with a less 
number of scrapers this team is idle much of 
the time. 

The road machine is one of the most gener- 
ally used of all road implements and scarcely 
needs any description. It may be briefly said 
to consist of a frame on four wheels, support- 
ing an adjustable blade, the front of which 
cuts a furrow while the rear end pushes the 
earth toward the centre of the road and dis- 
tributes it. The work of the grader is superior 
to that of the plough and the drag scraper, as 
the cut is uniform, whereas the plough cuts 
irregularly, and moves material in much larger 
quantities and at less cost than can be done by 
the drag scrapers. In using the road machine 
or road grader, it is best to put not more 
than from 4 to 6 inches of loose earth into the 
road at one working. The grading should be 
done early in the summer when the soil is damp. 
The loose earth will then pack and bake; it 
will not be so liable to become dusty in sum- 
mer, and will have ample time to settle before 



108 EOADS, PATHS AND BEIDGES 

the rains begin in the fall. This is one of the 
most important points in the whole problem of 
earth-road construction. 

The road machine is on the market in every 
conceivable design and varying in size from a 
machine suitable for two horses to one capable 
of withstanding a traction engine. It is most 
useful in crowning and smoothing the road and 
for opening ditches. What was said with ref- 
erence to the use of the plough is also true in 
regard to the use of the road machine. It is 
unwise to pull loose sand upon a sandy road, 
for to do so is only to make it deeper. On the 
other hand, if there is clay in the subsoil under 
the sand, it will improve the road to pull it up 
with a road machine. It is likewise bad man- 
agement to pull clay upon a thin coating of 
gravel or soil. The clay will hold water and 
make the gravel soften. 

It is a great mistake to pull clay from ditches 
upon a macadam surface with a road machine. 
For the same reason, it is a mistake to use a 
road machine indiscriminately and to pull ma- 
terial from the ditches upon a sand-clay or 
gravel road. Frequently turf, soil and silt 




THE SAXD-CLAY ROAD. 

1. (Top.) Spreading the clay on the sand. 2 
sand and clay. 3. Mixing with the disk-harrow. 
of laying a road-side drain. 



Plowing and mixing 
4. (Left.) Method, 



THE EAETH ROAD 109 

from the bottom of the ditch are piled in the 
middle of the road in a sort of ridge, or, if any 
effort has been made to spread it, ofttimes it is 
done in such a way as to make matters worse. 
Material containing grass or other vegetable 
matter should never be allowed to be placed on 
the road, unless it is a sand road and no clay is 
obtainable/ Weeds and grass should be burned 
or cut and removed before grading is begun. 
This simple plan will do much to relieve the 
objection often met with in working the road in 
the fall, when the ditches are filled with grass. 
To pull this mass of weeds and grass and sedi- 
ment into piles on the travelled track, besides 
making it uneven is the best way possible to 
start mudlioles. 

Another important point in building up a 
road with a road machine is to avoid building 
up too much at one time. It will be found that 
a road built up after using the road machine 
a number of times will stand far better than one 
built all at once. In the first instance, the ma- 
terial is brought up in thin layers and firmly 
packed before the next layer is brought up, and 
in that way the road is made up of a number of 



110 EOADS, PATHS AND BEIDGES 

thin layers, each one of which is well puddled 
and packed before the succeeding layer is 
added. It is too often the case that the road 
builder thinks he must have his road high in 
the first instance and, consequently, piles up 10 
or 12 inches of raw material at one time. The 
result is that when the rains come there are no 
fewer inches of mud in this newly worked road. 
This would not have occurred had the road fore- 
man taken more time and built up the road by 
degrees. 

It is also a common mistake to crown too 
high with the road machine. This is particu- 
larly noticeable when the road happens to be a 
little narrow. For this reason a road to be 
worked with a road machine should be of ample 
width, not less than 20 feet anywhere, and bet- 
ter from 20 to 24 feet wide. 



CHAPTEE V 

THE SAND-CLAY EOAD 

A SAiTD-cLAY Toad is composed of sand and 
clay mixed 'in snch proportions as to form a 
compact and firm support to traffic. The per- 
fect sand-clay road should be neither sticky nor 
sandy. The sand and clay may form a natural 
mixture, in which case, the road is termed a 
natural sand-clay road. The two materials 
may have become mixed in the fields along the 
road by successive cultivation of the soil, and 
if this soil is used in the construction of a 
road, it is known as a top-soil road. There 
are many varieties of clay, and consequently a 
wide variation in the characteristics of a sand- 
clay road. The quality of the sand is a vari- 
able factor, as it may range all the way from 
fine dust-like particles to coarse grains and 
gravel, and may be perfectly clean, or mixed 
with loam and other material. In consequence 
of these wide differences in the materials con- 
Ill 



112 EOADS, PATHS AND BEIDGES 

stituting sand-clay roads, it is impossible to 
maintain a uniform standard as to quality of 
the road, or the methods of construction. 

Properties of Sand, — Sand is, in general, 
composed of tiny grains of quartz. While 
quartz is one of the hardest minerals known, 
it possesses practically no binding or cement- 
ing power. The grains of sand, instead of 
cohering in a tough mass under the impact of 
traffic and the action of water, remain loose and 
shifting. Fine sand, when dry, is easily dis- 
placed by the wind, which produces in this way 
the ever-shifting sand-hills. No road is so 
difficult to travel as the road located through 
fine sand, and the difficulties are enormously 
increased when high winds prevail. 

Properties of Clay, — Clay is a decomposition 
product of the mineral feldspar. If the clay 
has been carried by running water and de- 
posited as sediment, it is known as ** sedimen- 
tary." If the feldspathic rock has disinte- 
grated in place, the clay is known as ** residual.'^ 
The sedimentary clay is finer grained than the 
residual, and is more sticky and plastic. In 
contrast with sand, which possesses no binding 



THE SAND-CLAY EOAD 113 

power, but is very hard, clay is a powerful 
binder. It does not, however, possess the qual- 
ity of hardness. 

It is evident, then, that in the construction 
of a sand-clay road the important property in 
the clay is its plasticity or tendency to become 
sticky and elastic when mixed with water. The 
clays whick are most plastic are called *'ball" 
clays. Another important property possessed 
by clays in widely varying degrees is the poros- 
ity, or capacity for rapid absorption of water. 
Clays which possess this quality in the highest 
degree fall to pieces under the action of water, 
and are called ^* slaking" clays. It will readily 
be seen that the plastic or ball clays will form 
a better and more powerful binder for sand- 
clay roads than will the slaking clays, but, on 
the other hand, they will be much more difficult 
to mix, as they disintegrate with far less rapid- 
ity. 

The shrinkage of clay is an important char- 
acteristic in connection with the building of 
roads. When water is mixed with clay, expan- 
sion results and, when the water evaporates, 
the clay contracts. This characteristic of ex- 



114 KOADS, PATHS AND BRIDGES 

pansion is much more pronounced in some clays 
than in others. It must be apparent that the 
clays which expand the least are preferable for 
road building, as they result in the least dis- 
placement of grains of sand, and, consequently, 
tend least to destroy the bond between the sand 
and clay. 

Gumbo or BucJcshot Soil, — This is of sedi- 
mentary formation and carries a considerable 
quantity of organic matter. A large area in 
the valley of the Mississippi river and its trib- 
utaries is composed of this kind of soil. The 
gumbo soil is composed of very fine particles, 
the colour of which ranges from grey to black, 
according to the amount of organic matter. 
Water is readily absorbed and causes the ma- 
terial to become exceedingly sticky; when dry, 
it breaks up or becomes granulated, which 
causes it to be termed ** buckshot soil.'' 

Sedimentary/ Loam, — In addition to the 
gumbo, which contains no sand, there are the 
sedimentary loams, which include all classes 
between gumbo and clean sand. As the per- 
centage of sand increases, the characteristics 
of the buckshot soil are less pronounced. The 



THE SAND-CLAY EOAD 115 

sand prevents grannlation of tlie soil, as well 
as marked contraction or expansion. Wliere 
the sedimentary loam contains a large propor- 
tion of sand, a reasonably good road can be 
made without the addition of other materials. 

Mixing of Sand and Clay. — The theory of the 
sand-clay road is very similar to that of the 
macadam road. In the latter rock-dust and 
screenings fill the voids between the angular 
fragments of stone and when wet serve as a 
cement or binder. The grains of sand may be 
likened to the angular fragments of stone and 
clay to the rock-dust binder. In the most suc- 
cessful sand-clay road just a sufficient amount 
of clay is used to fill the voids between the 
grains of sand. In this way the sand sustains 
the wear, while the clay serves as a binder. If 
too much sand is used, the result will be loose 
sand on the surface; if too much clay is used, 
the surface of the road will become sticky after 
rains. 

The best mixture of sand and clay can be 
made when the materials are wet, and particu- 
larly is this true of the plastic or ball clays. 
The more water used the better the mixture and, 



116 ROADS, PATHS AND BRIDGES 

if practicable, tlie materials should be puddled. 
If the road to be treated is sandy, clay should 
be hauled upon it, spread as uniformly as pos- 
sible, and all large lumps should be broken up. 
As soon as a heavy rain has softened the clay, a 
few inches of sand should be placed on it and 
then a thorough mixture should be brought 
about by means of a plough and a disc harrow. 
The result will be a successful mixture and a 
very disagreeable pasty mud. This condition 
will last for only a short time, and the road will 
eventually be all the better for it. The extent 
to which the mixing should be carried on will 
depend largely upon the character of the clay. 
If it is a plastic or ball clay, much greater effort 
will be necessary to obtain a complete mixture ; 
if, on the other hand, it is a slaking clay, the 
mixture will be much more readily obtained. 
This kind of clay is not as satisfactory, how- 
ever, as the ball clay, as its binding powers are 
much less. In selecting clay for road purposes, 
it is always best to select the stickiest clay 
available. A familiar test is to wet the thumb 
and place it against a piece of clay. If the 
clay sticks to the thumb, it is reasonable to sup- 



THE SAND-CLAY EOAD 117 

pose that it will stick to the sand ; if it will not 
stick to the thumb, it is safe to assume that it 
will be a poor binder in a sand-clay road. 

As the desirable proportions of sand and clay 
are such that the particles of clay barely fill the 
voids between the grains of sand, it is well, in 
determining the quantity of clay to be applied 
to a sand road, or sand to be applied to a clay 
road, to know approximately how much is 
needed. A simple method for determining the 
relative quantity is to take two glasses of the 
same size and fill one with the dry sand which it 
is proposed to use, and the other with water. 
The water should then be poured carefully in 
the glass of sand, and allowed to trickle down 
through the sand until it reaches the bottom of 
the glass. When the water has been poured 
into the glass of sand to the point of overflow- 
ing, we may assume that the voids between the 
grains of sand have been filled, and, conse-^ 
quently, the amount of water taken from the 
full glass would represent the volume of clay 
needed to fill the voids in a volume of sand 
equal to that in the other glass. It is better to 
use a little more sand than would appear to be 



118 EOADS, PATHS AND BEIDGES 

necessary, as the tendency is to underestimate 
the amount needed. In general practice, clay 
is placed on a sandy road to a depth ranging 
from 6 to 10 inches, while sand is placed on a 
clay road usually to a depth of from 6 to 8 
inches. 

Construction of a Sand-Clay Road, — The 
method of construction depends upon whether 
the suhsoil consists of sand or of clay. Good 
drainage is an essential feature of the sand- 
clay road, just as it is of all other types of road. 
A sandy or gravelly soil affords better natural 
drainage, and if the sand is present to an ex- 
ceptional extent, the only provision necessary 
for drainage will be to crown the surface of 
the road in the same manner as prescribed for 
earth roads. If the road is located through 
land that is so low as to be continually wet, it 
will be necessary, in addition to crowning the 
road, to provide wide ditches on each side, and 
to raise the roadbed a little higher than the 
surrounding ground. 

Drainage of a clay subsoil should be provided 
in exactly the manner as for earth roads in 
Chapter IV. 



THE SAND-CLAY EOAD 119 

After proper drainage has been secured, the 
roadbed should be crowned, beginning near the 
source of supply of the clay or sand. The clay 
should then be spread to a depth of from 6 to 8 
inches in the centre, sloping off gradually to a 
thin layer at the sides. Upon the clay should 
be placed a thin covering of sand. If the clay 
is of the plastic kind, it will then be necessary 
to plough and harrow it, taking advantage of 
rains to puddle the surface with a disc har- 
row. Sand should be gradually added until the 
surface of the road ceases to ball and cake. 
After the road is completed, if it loosens in dry 
weather, more clay should be added. The mix- 
ing of the sand and clay may be left to traffic, 
but this is an unwise procedure, as it means a 
very unsatisfactory road for a long period of 
time. 

If the clay is placed on sand to a depth of 6 
inches, a cubic yard of clay will cover 54 square 
feet, consequently, an 18-foot road, treated in 
this manner, would require 1 cubic yard of clay 
for each 3 feet of length. A mile of 18-foot 
road would, therefore, require 1,760 cubic yards 
of clay. The amount that can be hauled by the 



120 EOADS, PATHS AND BEIDGES 

average team varies from two-thirds to one 
cubic yard, according to the character of the 
road over which the hauling is done. 

If the clay subsoil is to be treated with sand, 
it should be ploughed and harrowed to a depth 
of about 4 inches. On this prepared subsur- 
face should be placed from 6 to 8 inches of clean 
sand, spread thickest at the centre and sloping 
to the sides, in much the same manner as the 
clay is applied to a sand road. These materials 
should then be mixed dry instead of wet, which 
is preferable when clay is applied to sand. Dry 
mixing is preferable because the clay can be 
better pulverised when in a dry state. After 
the dry mixing has been completed, the 
road should be puddled with a harrow after 
the first heavy rain. When the materials 
are thoroughly mixed and puddled, a road 
machine or grader should be used to give the 
proper crown to the road. If a horse roller is 
available, the road can be improved by the 
use of it. As it is impossible to determine 
exactly the proportions of sand and clay to be 
used in the first place, it is necessary to give 
careful attention to the sand-clay road for a 



THE SAND-CLAY EOAD 121 

considerable time after it is completed, in order 
that additional sand or clay may be applied as 
needed. 

Sand-clay roads have been built in the South 
at costs varying from $200 to $1,200 per mile. 
This wide variation in cost is due to the dif- 
ference in the proximity of sand and clay, cost 
of labour, 'weather conditions, efficiency of 
labour, management, etc. Under average con- 
ditions a sand-clay road 12 feet in width should 
cost from $500 to $600 per mile. 

The same considerations which should gov- 
ern in the location of earth roads and in the 
avoidance of steep grades, apply with equal 
force to the sand-clay road. 

Sand Roads, — ^Where roads are composed of 
deep sand, and where clay is not available, it 
is impossible to make the road satisfactory for 
traffic, but it is possible to make at least a slight 
improvement. 

Dampness is beneficial to a sand road, and it 
is well known that wet sand is easier to travel 
over than dry sand. Consequently, it is better 
to reverse, to a certain extent, the rules of drain- 
age which apply to earth and sand-clay roads. 



122 EOADS, PATHS AND BEIDGES 

The surface of a sandy road should be level and 
may even be slightly concave, provided the lon- 
gitudinal grade of the road is very slight. 
Otherwise, to make a road concave would sim- 
ply be to transform it into a ditch, which would 
soon be cut into deep gulleys. Fortunately, in 
almost all cases, sandy roads are naturally 
level. 

Shade is injurious to roads composed of clay 
or loam, as it prevents the road from drying out. 
A sand road, however, should have as much 
shade as possible in order to prevent it from 
drying out. In order to overcome the shift- 
ing, unstable character of the sand, grass should 
be encouraged wherever possible. In fact, any 
vegetable matter that can be made to grow on 
a sand road, or close up to a sand road, is 
beneficial. Even if the roots do not spread out 
into the travel way, the leaves and twigs from 
bushes will fall into the road and aid to a slight 
extent in providing a binder. If the road is 
sufficiently wide, half of it could be planted in 
grass, and traffic could be required to use the 
other half; when the grass is mature, traffic 



THE SAND-CLAY EOAD 123 

could be shifted and the other half planted to 
grass. Any vegetable fibre on a sand road is 
beneficial, but is of necessity only a temporary 
expedient. 



CHAPTEE VI 
THE GEAVEL EOAD 

Gravel consists of small, partially rounded 
fragments of stone produced from larger bodies 
of rock through the action of ice or water. 

The best gravel beds are found in the Glacial 
Drift, which covered Canada and that portion 
of the United States north of a line running 
from the Atlantic coast a little south of New 
York City, in an irregular direction to Cincin- 
nati, thence through Topeka, Kans., and north 
and west to the Pacific Ocean. The glacial ice- 
sheets carried large quantities of stone from the 
original rock ledges and ground them to small 
pebbles. In general it may be said that this 
glacial gravel is found in western Pennsyl- 
vania, most of Ohio, northern Indiana, northern 
Illinois, and in most of the northwestern States. 
The gravel which exists south of the glacial 
district, with the exception of river gravel, has 
been in most cases produced by a slow disin- 
tegration of the rocks in place. 

124 



THE GEAVEL EOAD 125 

Gravel has been extensively used in certain 
sections of the South for road building, notably 
in Chatham County, Ga., of which Savannah 
is the county seat, and Montgomery County, 
Ala., while in northern Georgia, Alabama, 
Mississippi and Tennessee excellent roads have 
been built from abundant chert-gravel deposits. 
The gravel deposits in the South, however, are 
local and limited in extent, and are confined 
principally to the States of Virginia, North and 
South Carolina, Tennessee, Georgia, northern 
Mississippi, western Kentuck}^, Alabama and 
Arkansas. Texas is well supplied with gravel 
in the northeastern portion of the State. The 
delta regions of Mississippi and Louisiana are 
almost devoid of road-building materials, and 
the gravel deposits are small in quantity and of 
inferior quality. Arkansas, as a whole, is not 
supplied with good road material, but there are 
extensive deposits of gravel in the southwest 
portion of the State. In Kentucky the gravel is 
limited to local deposits along streams. 

Qualities of Gravel. — Eoad-building gravel 
should possess three important qualities : hard- 
ness, toughness, and cementing or binding 



126 EOADS, PATHS AND BEIDGES 

power. Of these three qualities the last is 
the most important. This binding quality is 
due in part to the presence of iron oxide, lime, 
or ferruginous clay, and in part to the angu- 
lar shape and size of the pebbles composing 
the gravel. A good way to determine whether 
or not a gravel is suitable for road building is 
to notice its position in the pit. If the banks 
remain vertical after exposure to the weather, 
it is a reasonable inference that the material 
possesses a high cementing value and will 
cement and compact well in the road. Blue 
gravel is universally conceded to be the best 
for road construction, because it is usually 
derived from trap rocks. As the pebbles com- 
posing the gravel retain the characteristics 
which they possessed when forming part of the 
larger rock masses, it follows that as trap rock 
is considered an excellent material for road 
building, trap-rock gravel should occupy the 
same relative rank among the gravels. Lime- 
stone is, generally speaking, a soft rock, and 
consequently limestone gravel (which is quite 
rare) will usually be found soft and will wear 
rapidly. Quartz possesses practically no bind- 



THE GEAVEL EOAD 127 

ing power, although it is a very hard mineral. 
Therefore, gravel which contains an exception- 
ally large percentage of quartz will not prove 
successful, unless a good binder is added. On 
the other hand, the chert gravels, which are 
composed mainly of amorphous or non-crys- 
talline quartz, possess a very high binding 
value. 

The shape and size of the pebbles composing 
the gravel have an important bearing upon its 
value as a road material. In order that the 
material may bond readily, the pebbles should 
be angular, and should vary in size so that the 
smaller fragments may fill the voids between 
the larger pieces. The largest pieces of gravel 
should not be more than two or two and 
one-half inches in their greatest dimensions. 
Otherwise, the large fragments will fail to com- 
pact and will work to the surface. On the other 
hand, the gravel should not be too fine, as in 
this case it will be equally difficult to consoli- 
date. Many road builders consider the grada- 
tion in sizes the most important quality of road- 
building gravel. 

The angular shape of the gravel is essential, 



128 EOADS, PATHS AND BEIDGES 

in order that a mechaiiical bond may be secnred. 
Gravel obtained from streams is inferior to 
pit gravel, for the reason that the constant 
action of water has worn the pebbles smooth 
and partially round, so that it is very difficult 
to obtain the mechanical bond necessary in the 
construction of gravel roads; moreover prac- 
tically all of the fine binding material has been 
removed by the same agency. Even if a fer- 
ruginous clay is mixed with the river gravel, 
the result is not likely to be as satisfactory as 
that obtained by the use of pit gravel. 

When the gravel is taken from the pit, it 
should not contain more than one-fourth of its 
volume in sand or clay. Pit gravel frequently 
contains too much clay or earthy matter, while 
river gravel may have too much sand. In such 
cases, the gravel should be screened so as to 
eliminate the material which is too fine and that 
which is too coarse. The screens should have 
meshes of about 2%, 1% and % inches. Where 
gravel is screened in this way, it can be laid in 
courses on the road. The fragments which pass 
through a 2%-inch screen may form the bottom 
course ; those which pass a 1%-inch screen, the 




THREE SORTS OF GOOD ROAD. 

1. (Top.) A well-constructed gravel road near Baker City, Oregon. 
2. A road surfaced with slag screenings, to which quick lime was 
added as an additional cementing agent. 3. A sand-clay road near 
Aiken, S. C. 



THE GEAVEL ROAD 129 

middle course; and the fine material may be 
nsed as the top course, or binder. 

Some highway engineers favour the use of 
clay as a binder in gravel-road construction, 
where the gravel requires the addition of a 
binder. The clay should be used very spar- 
ingly, however, as it absorbs water and causes 
the road to become soft and muddy. When the 
clay dries, it contracts and causes the road to 
crack. Clay is also affected by frost. Loam is 
frequently used as a binder for gravel roads, 
and consists of sand and some vegetable mat- 
ter, lime, etc., mixed with clay. It possesses 
about the same qualities as a clay binder. The 
best binder of all is iron oxide, which is fre- 
quently found coating the pebbles. 

Chert and Chert Gravel, — Chert is a silicious 
rock and occurs usually in limestone and sand- 
stone formations. It is generally believed to 
be formed by a chemical precipitation from sea 
water. The material is found sometimes com- 
pletely covering the ground; sometimes in the 
beds of streams and narrow valleys where it 
has been redeposited by the action of water; 
and in other cases in banks and pockets on hill 



130 EOADS, PATHS AND BEIDGES 

and mountain sides. Bank clierts usually occur 
in nodular masses, but where they are found in 
stream beds tbey are often broken into angular 
fragments, varying in size from 1 to 6 inches. 
Bank cherts are easily quarried by blasting and 
the lumps reduced to proper size by napping 
hammers or by rolling. 

Where these materials are found in the beds 
of streams they are commonly called gravel. 
Creek gravel formed from chert is usually of 
uniform size and comparatively clean, while the 
bank gravel often contains earthy matter and 
fine particles of the same material. The creek 
gravel wears the best, but it does not bind as 
readily, or form as smooth a surface as the bank 
deposits. Where both creek and bank cherts 
are available, good results can be obtained by 
using the former for foundation and the latter 
for the wearing or binding course. A road 
built in this way at Florence, Ala., under the 
direction of an expert of the Office of Public 
Eoads, in 1898, is said to be in perfect condi- 
tion at the present time, although it has never 
been resurfaced. Chert is found in the south- 
ern portion of the Appalachian Mountains, 



THE GEAVEL EOAD 131 

along the Ozark footliills, in southern Illinois, 
southern Missouri, northern Arkansas and 
eastern Oklahoma. 

Gravel-road Construction, — The first step in 
the construction of a gravel road is to obtain 
the desired grade, after which the road should 
be given a suitable cross-section, or crown, so 
that the centre of the finished roadway will be 
from 6 to 8 inches higher than the edge of the 
gravelled portion for a 16-foot road. About 
the same ratio of height to width should be 
maintained for other widths than 16 feet. The 
subgrade should be thoroughly rolled and com- 
pacted, and all loose and unstable earth removed 
and replaced by sand and gravel. The gravel 
should then be placed on the subgrade to a total 
depth of from 8 to 12 inches in the centre, taper- 
ing ofiF to a depth of from 4 to 6 inches on the 
sides. 

Sometimes it is advisable to screen the gravel 
and place it in layers, and the coarser should be 
used for the foundation, as previously ex- 
plained. The thickness of the respective 
courses should be approximately from 4 to 6 
inches for the foundation course, from. 3 to 4 



132 ROADS, PATHS AND BEIDGES 

inches for the second course, and from 1 to 2 
inches for the surface, or binding course. 
Each layer should be thoroughly sprinkled and 
rolled with a roller weighing not less than 2 tons, 
and at least 2% feet long. If a roller and sprin- 
kler are not available, the road should be con- 
structed in the spring, as the successive rains 
will cause the material to pack much better than 
if the road were built in the dry, hot summer or 
early fall. This is an exceedingly important 
point and one which is generally overlooked. 
If the gravel fails to compact, a thin layer of 
crushed-rock screenings applied to the surface 
will be found exceedingly beneficial. 

McAdam condemns the practice of dumping 
gravel indiscriminately on the road and leaving 
it for traffic to compact. The following quota- 
tion taken from his report, published in 1824, 
applies with equal force to present-day condi- 
tions. 

'*The formation of roads is defective in most parts 
of the county; in particular the roads around Lon- 
don are made high in the middle, in the form of a 
roof, by which means a carriage goes upon a danger- 
ous slope, unless kept on the very centre of the road. 




CONSTRUCTING A MACADAM ROAD. 

The three courses of stone are shoAvn in relative size : the hirgest 
("No. Is'') at the bottom; the second, smaller (''No. 2s''), and the 
top or binder course of screenings; also a view of a road, showing its 
foundation, rolled, and a first course applia^. 



THE GRAVEL ROAD 133 

*' These roads are repaired by throwing a large 
quantity of unprepared gravel in the middle, and 
trusting that, by its never consolidating, it will in 
due time move towards the sides/' 

The principal causes of failure in gravel-road 
construction may be summarised as follows : 

1. Poor material. 

2. Spreading the gravel in dry weather; dumping 
it in heaps and leaviug it for traffic to compact. 

3. Placing the gravel on surfaces filled with ruts 
and holes. 

4. Insecure or poorly drained foundation. 

5. Improper construction of ditches or culverts. 

6. Making the road so narrow that wagons will 
track, thereby forming deep ruts. 

7. Failure to fill ruts and holes with gravel. 

The information given in Chapter IV regard- 
ing drainage applies with equal force in the con- 
struction of gravel roads, and should be fol- 
lowed faithfully, as otherwise a poor road will 
result, even if the greatest care is used in the 
selection of materials and in placing them upon 
the subgrade. 



CHAPTER VII 

THE BROKEN-STONE ROAD 

The term ^^ macadam" is generally under- 
stood to mean a particular type of road. That 
this type of construction is different from that 
used by John L. McAdam, and named after 
him, need cause but passing comment. Mod- 
ern machinery and modern science have worked 
many changes, but the fundamental principles 
demonstrated by McAdam, that the foundation 
must be well drained in order properly to carry 
the loads which come upon the road; and that 
an aggregate of broken stone can be made to 
cement, or knit together, so as to be waterproof 
and firm enough to support trafiSc, still holds 
good. McAdam ^s own explanation of his 
method is clear, concise and to the point. In 
his report, published in 1824, he said: 

*'The roads can never be rendered thus perfectly 
secure until the following principles be fully under- 

134 



THE BROKEN-STONE ROAD 135 

stood, admitted, and acted upon: namely, that it is 
the native soil which really supports the weight of 
traffic; that while it is preserved in a dry state, it 
will carry any weight without sinking, and that it 
does in fact carry the road and the carriages also; 
that this native soil must previously be made quite 
dry, and a covering impenetrable to rain, must then 
be placed over it, to preserve it in that dry state; 
that the thickness of a road should only be regulated 
by the quantity of material necessary to form such 
impervious covering, and never by any reference to 
its own power of carrying weight. The erroneous 
opinion so long acted upon, and so tenaciously ad- 
hered to, that by placing a large quantity of stone 
under the roads, a remedy will be found for the sink- 
ing into wet clay, or other soft soils, or in other words, 
that a road may be made sufficiently strong, arti- 
ficially, to carry heavy carriages, though the subsoil 
be in a wet state, and by such means to avert the 
inconveniences of the natural soil receiving water 
from rain, or other means, has produced most of the 
defects of the roads of Great Britain. . , . 

*' Every road is to be made of broken stone with- 
out mixture of earth, clay, chalk, or any other matter 
that will imbibe water, and be affected with frost; 
nothing is to be laid on the clean stone on pretence of 
binding; broken stone will combine by its own angles 
into a smooth, solid surface that can not be affected 
by vicissitudes of weather, or displaced by the action 
of wheels, which will pass over it without a jolt, and 
consequently without injury." 



136 EOADS, PATHS AND BRIDGES 

In addition to the modifications due to prog- 
ress, other modifications of a local character 
must be made because of climate, topography, 
nature of traffic, character of the local stone, 
etc. Thus, while we can specify the construc- 
tion for any given road to the smallest detail, 
it must always be borne in mind that different 
conditions necessarily demand changes, at least 
in the minor details. Furthermore, a proper 
recognition and appreciation of these details 
will invariably save money for the taxpayer. 

While the macadam, or broken-stone, type of 
road is particularly well adapted to those carry- 
ing a moderate traffic, it is not economical as a 
pavement for city streets carrying heavy traffic, 
or on roads subjected to heavy automobile 
traffic, unless some special type of binder other 
than the stone dust is used. In some ways a 
macadam road resembles quite closely a well- 
built gravel road, but, as a rule, it will stand 
heavier traffic and wear better, since the me- 
chanical bond between the aggregates is 
stronger than that which can be supplied by 
the more or less rounded pebbles of the gravel. 
Even in regions where gravel is abundant, a 



THE BEOKEN-STONE EOAD 137 

macadam surfacing may prove more econom- 
ical on tlie more heavily trafficked sections 
where the gravel does not furnish a sufficiently 
strong bond to withstand the requirements of 
the traffic. 

Width of Surfacing, — Experience has shown 
that for ordinary country roads the macadam 
surface need not be more than from 13 to 16 
feet wide, if suitable earth shoulders are built 
on each side. Thirteen feet allows two vehicles 
to pass each other safely. Sixteen feet is more 
satisfactory, especially when more or less frac- 
tious teams are passing automobiles. If the 
stone is less than 13 feet wide, there is a like- 
lihood that the edges of the macadam will be 
sheared off by the wheels, unless the shoulders 
are made of especially good material. In fact, 
a width of less than 13 feet is of doubtful value, 
unless the surface portion is reduced to the very 
narrow width of 8 or 9 feet. This serves fairly 
well as a single track, where the prevailing 
loaded traffic is in one direction, and a good 
earth road is provided on one or both sides of 
the macadam. 

There are many communities where during 



138 EOADS, PATHS AND BRIDGES 

tlie greater part of the year a well-kept earth 
road is about all that is desired, but when, for 
the few months during the winter or spring, 
these earth roads become all but impassable. 
Here a narrow strip of macadam with a well- 
kept earth road on one or both sides will some- 
times answer the purpose at a much lower cost 
than a standard-width road of from 13 to 15 
feet; for, during good weather, practically all 
the traffic, excepting the very heavy loads, will 
use the more resilient earth road, while during 
bad weather all will use the macadam as far as 
possible. The light traffic will turn out on the 
earth road to pass the loaded teams. "What- 
ever may be the width of the stone, however, the 
shoulders should be firm enough to permit occa- 
sional passage of wheels. 

In the past years it was almost the universal 
practice to build the macadam roads very thick. 
Of course, this required a very large amount 
of material, and made the cost extremely high. 
A comparatively few years ago, roads less than 
eight inches thick were rarely heard of, and not 
infrequently a thickness of at least 12 inches of 
macadam was thought to be necessary for a 



THE BEOKEN-STONE EOAD 139 

good road. To-day one of the most conspicuous 
means of reducing the cost has been by decreas- 
ing the thickness of the surfacing, and we find 
many roads supporting quite heavy traffic, 
although only 5 or 6 inches in thickness. Four 
inches of macadam after rolling is about the 
least thickness which is practicable, and, except 
in unusual- cases, a depth greater than 8 inches 
after rolling is unnecessary. 

A macadam surfacing should be hard, smooth 
and impervious to water. Much attention must 
also be given to the foundation, which should 
be firm and sufficiently strong to sustain any 
load likely to come on the road at any time of 
the year. 

Quarrying for Material, — In opening a new 
quarry careful attention should be given to the 
inclination of bed joints or seams, which, for 
economical quarrying, should be parallel with 
and dip toward the working face of the ledge. 
The drainage of the quarry should also be con- 
sidered and the floor level should, wherever pos- 
sible, be so arranged that the water can be 
drained from the working face by gravity. 
Wherever possible the ledge should be opened 



140 EOADS, PATHS AND BEIDGES 

where the overburden is light and where but 
little expensive stripping will be necessary. The 
quarry should be located, if possible, in such a 
position that gravity will assist in handling 
materials, so that tram-cars may carry material 
from the floor of the quarry to the mouth of the 
crusher by gravity. The loaded car in its down- 
ward trip may be made to drag the empty car 
back to the floor of the quarry. If the quarry 
is located in a pit it will be necessary to provide 
power for this purpose; furthermore, a consid- 
erable expenditure for pumping water will be 
entailed, aside from that necessary for opera- 
ting tramways by mechanical power. 

In removing the overburden the earth should 
be carried far enough away from the quarry 
not to interfere with future operations. When 
the overburden is of a tenacious nature, or when 
it is frozen, it may be loosened by sinking a 
few holes from two to five feet in depth and by 
charging them with explosives. Low grade 
dynamite is suitable for this purpose. If the 
overburden consists of earth or gravel, it can 
sometimes be removed economically by the use 
of water and a flume. 




*^ _ y>L * '<i 



BAD KUAD-ruXSTKLC'TlOX. 

1. (Top.) Loose stone thrown on and left to be packed l)y traffic 
2. Raveling- of macadam caused by use of stone which has little bind- 
ing p )wer. 3. Result of the use of quartz, lacking binding power; 
also, evidence of a liad foundation and poor drainage. 



THE BEOKEN-STONE EOAD 141 

As road-building rocks are usually hard and 
tough, the drill-holes in the quarry face can be 
more economically placed by means of steam 
or compressed-air drills than by the use of hand 
drills. For gravels, cherts and various other 
soft materials used in road building, hand or 
churn drills may, however, be used to advan- 
tage. If ^a steam drill is employed, the steam 
may be procured from the boiler which operates 
the crushing plant and be conveyed to the 
drilling machine by small iron pipes. The 
quarryman should use good judgment in the 
selection of the positions where the holes are 
to be bored. He should consider the effects of 
the action of the explosive on the rock before 
him, and the relation of the bore-holes to the 
face of the quarry. In this connexion it is 
necessary that he examine carefully the fis- 
sures in the rock before the holes are drilled. 
To get the best results the rock should present 
an unsupported face on every side, but in ordi- 
nary practice this condition seldom obtains. 
The wall of the quarry is usually vertical, and 
the two free faces are the top and the breast of 
the rock. Ordinarily, therefore, the bore-holes 



142 ROADS, PATHS AND BRIDGES 

should be placed as nearly parallel to the longest 
free face of the rock as possible. 

The object in quarrying rock for road build- 
ing is to shatter the materials as much as pos- 
sible, and for this reason high explosives are 
preferred. Dynamite is a rapid and violent 
explosive, and produces effects very suddenly. 
It is, therefore, better adapted than giant 
powder for quarrying rock for road building. 
Dynamite dislodges the rock and, if properly 
used, reduces most of it to a size suitable for the 
crusher without sledging ; consequently, the cost 
of quarrying with high explosives is cheaper 
than with low explosives. If giant powder is 
used, it is necessary either to make larger bore- 
holes or to increase the number to obtain the 
same results. 

It may be noted in this connexion that any ex- 
plosive containing nitro-glycerin is commonly called 
dynamite. Dynamite is usually made by partly satu- 
rating some porous material with nitro-glycerin. The 
percentage of nitro-glycerin usually contained in 
dynamite varies from 40 to 75. If by the use of the 
40 per cent, dynamite it is found that the rocks are 
blown out in chunks too large for the crusher, then it 
is advisable to use the 75 per cent, nitro-glycerin. A 



THE BEOKEN-STONE EOAD 143 

few experimental shots with dynamite of different 
grades will indicate the percentage which can best be 
employed in any particular quarry. 

Crushing, — A crusher for road building 
should be provided with a suitable elevator and 
with screens for separating the materials into 
their proper sizes. Eevolving screens for small 
plants are usually about 10 feet long, 32 inches 
in diameter, and should revolve at the rate of 
about 20 revolutions per minute. The screen 
is divided into sections, and the lengths of each 
one and the sizes of holes for diabase and other 
harder rocks should be about as follows : First 
section, 3% feet long, holes % inch in diameter; 
second section, 3 feet long, holes 1% inches in 
diameter ; and third section, 3 feet long, holes 3 
inches in diameter. No hard stone larger in 
diameter than will pass through the 3-inch holes 
in the screen should be used in a macadam road, 
and, therefore, stones too large to go through 
the larger holes should be returned to the 
crusher by gravity or by means of a belt con- 
veyor, where they are recrushed. If the tail- 
ings are not recrushed, then they should be 
eliminated from tlie work. For limestones and 



144 EOADS, PATHS AND BRIDGES 

the softer varieties of rock the size of holes in 
the first and second sections of the screen may 
be increased to % inch and 2 inches, respec- 
tively. A portion of the screen which contains 
the %-inch holes should be provided with a dust 
jacket, as the softer rocks usually produce more 
dust than is necessary for binding material. 
The jaws of the crusher should be so set as to 
make as few tailings as possible, and the lengths 
of the screen sections should be adjusted to the 
same purpose. 

For receiving the various sizes of crushed 
rocks, bins with slanting metal bottoms and 
sliding doors should be provided, so that the 
material can be loaded into wagons by gravity. 
Partitions should be built in the bins so as to 
keep the differently sized materials separated. 

Two types of crushers are now commonly used in 
crushing rock for road building. One is the jaw type 
of crusher, generally used for small portable plants. 
In this machine one of the jaws moves backward and 
forward by means of a toggle joint and an eccentric, 
and the stone descends as the jaw recedes. As it re- 
turns, it catches the stone and crushes it. The maxi- 
mum size of the products is determined by the dis- 
tance the jaw plates are apart at the lower edge. 




ROAD-MAKIXG MACHINERY. 

1. Rolling the second course of macadam. 2. A portable stone 
crusher. 3. A spreader. 



THE BEOKEN-STONE EOAD 145 

The gyratory crusher consists of a solid conical steel 
shaft supported by a heavy mass of iron somewhat 
like an inverted bell. By means of an eccentric, the 
rotary motion given to the shaft is such that every 
point of its surface is successively brought near the 
surface of the ''bell/' and the rock caught between 
the shaft and the bell is crushed. The gyratory 
crusher will not produce as many flat pieces or tail- 
ings as the jaw crusher, because the stones have to 
come in contact with two curved surfaces at the same 
time before they are broken. It is peculiarly 
adapted, therefore, to crushing rocks which are more 
or less laminated. 

Large stationary plants are, as a rule, desirable 
only where the broken stone must be shipped by rail. 
There are several portable plants on the market 
which may be bought at prices ranging from about 
$1,500 to $2,500, and which are well adapted for 
country use. The complete plant includes stone 
crusher and engine boiler, portable bins, revolving 
screens and an elevator for lifting the broken stone 
from the discharge of the crusher into the screen. 
These outfits are mounted on wheels, so as to be 
readily moved from place to place. Where no special 
difficulties are encountered in setting up the plant, 
it may be moved from one place to another at a cost 
of from $50 to $100. The average output of such a 
plant as has been mentioned is from 75 to 100 cubic 
yards every day. The amount of the output, how- 
ever, will depend very largely on the character of the 
stone which is being crushed, and the ability of the 



146 EOADS, PATHS AND BEIDGES 

man who has the plant in charge. The hard usage 
to which the crusher is subjected naturally entails 
much repair work, and requires constant and skilful 
attention in order to secure the best results. "Where 
there is a choice as to the location of the crusher, it 
should be placed at about the middle of the stretch 
of road to be built, so that the output can be hauled 
in both directions. The distance which the broken 
stone can economically be hauled will generally not 
exceed over one mile. This would tend to show that 
unless other conditions are involved, two miles of 
road is about all that can be economically constructed 
from each setting of the crusher. In general it will 
also be found advisable to set the crusher at the 
quarry and haul the crushed stone to the road, rather 
than to set the crusher at the road and haul the quar- 
ried stone to the crusher. 

Every effort should be made to reduce the 
number of times which the rock must be han- 
dled. By setting the crusher at the quarry, the 
tram-cars can often be rigged so as to be ope- 
rated, either by cable with the power supplied 
by the crusher engine, or by gravity, and the 
stone conveyed direct from the ledge and 
dumped on the crusher platform. With, this 
arrangement, moving the stone will require the 
minimum amount of hand labour. 

In some places, it may be found more econom- 



THE BEOKEN-STONE EOAD 147 

ical to have the stone shipped in from some per- 
manent crushing plant than to purchase a 
crushing outfit ; and this feature should be care- 
fully considered. It is well to study the char- 
acter of the local stone, to ascertain whether it 
is such as to justify its use, or whether it would 
not be more economical to import a better stone, 
at least f or.the surface course. 

Boad'Building Machinery. — A roller oper- 
ated by mechanical power has almost entirely 
superseded the old-fashioned horse roller. Its 
weight is an important consideration for two 
reasons : First, the cost of the roller is approx- 
imately so many dollars per ton ; second, exist- 
ing bridges and culverts are rarely strong 
enough to carry the heaviest rollers. For coun- 
try roads, experience has demonstrated that a 
10-ton roller is sufficiently heavy. There are a 
number of excellent makes of such rollers on 
the market, which may be had at prices ranging 
from about $2,000 to $3,500. 

Another essential in the construction of a 
macadam road is the sprinkler. A sprinkler 
with a capacity of from 450 to 600 gallons is 
usually sufficient. Local conditions such as 



148 EOADS, PATHS AND BEIDGES 

grades and tlie distance that water must be 
hauled will determine the proper size. The 
sprinkler should be provided with extremely 
broad tires, to assist in rolling the partially con- 
solidated macadam, rather than to loosen it or 
to form ruts. 

The road machine, or grader, is a most valu- 
able implement, and one which is often over- 
looked. All too often its only use, or rather 
misuse, is that of scraping back upon the road 
the worn-out material which has been washed 
into the gutters. The road machine can and 
should be used to good advantage in shaping the 
road preparatory to the application of the 
broken stone. It is not uncommon to find that 
with a skilled operator the entire subgrade can 
be shaped with the road machine, thus doing 
away with considerable hand labour. 

Where a large amount of road building is 
done automatic spreading wagons will prove 
economical, but since such wagons can, as a 
rule, be used for no other purpose, they would 
prove »a financial burden to a contractor or a 
municipality that was doing but a small amount 
of road building. 



THE BROKEN-STONE EOAD 149 

Weight of Broken Stone. — Broken stone is 
frequently sold by weight. Before estimating 
the cost of a road, when a stone is to be paid 
for thus, the road officials must know how much 
the stone will weigh per cubic yard. The erro- 
neous impression that all stone weighs the same 
per unit volume is quite general throughout the 
United States. One often hears it stated that 
a cubic yard of broken stone weighs a ton and 
one-third, regardless of the kind of stone. The 
following table taken from Farmers' Bulletin 
No. 338, United States Department of Agricul- 
ture, gives the specific gravity and weight of a 
number of the more common rocks : 

SPECIFIC GRAVITY AND WEIGHT OF VARIOUS 

ROCKS. 





Name 




Specific 
gravity. 


Weight per 

cubic foot of 

solid rock. 


Weight! per 

cubic yard of 

solid rock. 


3 ft 

03 


X 




4 




ii 


> 

< 


Max. 


Min. 


Av. 


09 


05 










3 
124 

33 
60 


Peridotite (trap). 
Diabase (trap) . . . 
Diorite (trap) . . . 
Schist 


3.55 
3.20 
3.35 
3.20 
2.80 
3.10 
3.10 
3.00 


3.25 
2.60 
2.70 
2.65 
2.50 
2.50 
2.00 
2.00 


3.40 
2.95 
2.85 
2.90 
2.65 
2.70 
2.65 
2.65 


221 
200 
209 
200 
175 
193 
193 
187 


•203 
162 
168 
165 
156 
156 
125 
125 


212 
184 
178 
181 
165 
168 
165 
165 


2,984 
2,700 
2,821 
2,700 
2,362 
2,605 
2,605 
2,524 


2,741 
2,187 
2,268 
2,227 
2,106 
2,106 
1,687 
1.687 


2,862 
2,484 
2,403 
2,443 


11 


Felsite 


2,227 


53 
358 
106 


Quartzite 

Limestone 

Granite 


2,268 
2,227 
2.227P 













1 Tons of 2,000 pounds. 



150 EOADS, PATHS AND BEIDGES 

The above table gives the weights of the solid 
rock as it is found in the quarry. If it is 
assumed that the volume of the stone, after it is 
crushed and lies in the bins, has a void of 50 per 
cent., and the average weight of peridotite is 
compared with the average weight of granite, it 
will be seen that the crushed peridotite weighs 
1.43 tons to the cubic yard, while the granite 
weighs only 1.11 tons. The heaviest diorite 
weighs 1.41 tons to the cubic yard, and the light- 
est only 1.13 tons. Ditferences as marked as 
these emphasize the great need of careful deter- 
mination of the weight of the material before 
any contracts are let. 

When broken stone is purchased by measure- 
ment, from cars or in wagons, the specifications 
should always state where the measurements 
are to take place. It is evident that the stone 
will occupy considerably more space when it is 
first loaded into either the car or the wagon 
than after it has been jolted about in transpor- 
tation, either by rail or on the wagon road. 

Earth Work, — No earth work should be un- 
dertaken until the grades have been definitely 
established and the grade stakes set. Such 



THE BROKEN-STONE EOAD 151 

work of course belongs to the engineer, and 
this holds true whether it be in regard to the 
construction of a new road or the reconstruction 
of an old one. In fixing the grades, care should 
be taken to adjust the cuts and fills so that there 
will be no undue amount of waste or borrow as 
explained in Chapter IV. No extreme refine- 
ment, such as is sometimes practised on railroad 
work in balancing the cuts and fills, is necessary 
in highway construction. In most States, the 
right of way provided is wider than the width 
necessary for the roadway. Therefore, where 
more fill is needed, the additional material can 
readily be secured by simply widening the adja- 
cent cut to the desired extent, and, where the 
cuts are in excess, convenient wastage can read- 
ily be found by simply widening the adjacent 
fills. This does not mean, however, that the 
work is to be done in a haphazard manner, but 
that the computations and surveys shall be 
carefully made and where additional widenings 
are needed they shall be immediately staked out 
on the ground. 

It is obvious that the subgrade, or foundation, 
of a road is the part most nearly permanent. 



152 EOADS, PATHS AND BEIDGES 

The grades should, therefore, be studied most 
carefully, since they cannot be changed without 
great expense. 

Drainage. — Drainage is absolutely essential 
to macadam, as well as to any other form of 
road. The road should be so constructed that 
it will shed the water to the side ditches as rap- 
idly as possible, and the side ditches in turn 
must be of such size and slope as to remove the 
water from the road quickly and completely. 
For a narrow macadam road, a crown or side 
slope of % of an inch to the foot for the mac- 
adam portion will be about right. For a wide 
road this will give too much crown, and the 
side slope must be reduced to % or perhaps % 
inch per foot. The slope of the shoulders 
should be equal to, or perhaps in general, a 
little greater than that of the macadam. The 
slope of the side ditches must be made to vary 
somewhat with local conditions. If possible the 
slope should be sufficient, so that the ditches 
will be self-cleansing, and not have a tendency 
to fill with detritus washed from the road. 
On the other hand, the slope should not be so 
great as to cause erosion. Where steep grades 



THE BROKEN-STONE ROAD 153 

cannot be avoided, the gutters or side ditches 
must be either paved, or else stops placed at 
occasional intervals to check the velocity of the 
water. Nor should the practice, which is so 
often found, of carrying the water along the 
road for long distances, be tolerated. Water 
is always an element of danger to a road, and 
should be gotten rid of as quickly as possible. 
Every outlet should be utilised for this purpose, 
even though it involves the construction of a 
few more cross-drains. 

Surface water is not the only danger to a 
macadam road. In many places special atten- 
tion must also be given to the underground 
waters. It is sometimes possible to drain the 
road with open side ditches, but deep ditches 
on the roadside are an element of danger, and, 
where the ground waters are to be removed 
from the road, it will usually be preferable to 
employ tile drains. Sometimes the direction 
of the movement of the underground water is 
such that a single drain on one side of the road 
will be sufficient. In other cases, a drain will 
be required on both sides. The best practice in 
road drainage is to remove the ground water 



154 EOADS, PATHS AND BRIDaSS 

to such a depth that there will be no danger 
from the heaving action of the winter frosts. 
The drains usually consist of narrow trenches 
filled more or less completely with broken stone 
or gravel, and having a drain tile near the bot- 
tom. The tile used is ordinarily the open-joint 
drain tile, which must be laid true to grade, and 
provided with free outlet. Sometimes the pipe 
is omitted and the trench is filled entirely with 
stone, when it is called a blind drain. This 
practice, however, is not to be recommended 
where large quantities of water need to be re- 
moved at any time during the year. 

Cross-drains may be made of concrete, or, if 
not large, iron pipe or vitrified clay tiles may be 
used. Recent improvements in the manufac- 
ture of non-corrosive steel have made that 
material available for this purpose. Vitrified 
clay tile has also been used, as well as abused, 
to a large extent in past years. It should 
never be laid close to the road surface, nor 
where there is the least danger of the drain 
ever clogging in cold, winter weather. Many 
failures of clay tile have been caused in the 
northwestern States by a winter thaw during 



THE BROKEN-STONE ROAD 155 

which the tiles become clogged with slush, ice 
and water, and then this thaw is followed by a 
freeze, which, of course, bursts the tile. Of all 
materials at present, concrete seems the most 
durable, as well as, in the majority of cases, the 
most economical. Where large bridges or cul- 
verts are required, detailed desigTis should al- 
ways be made before construction. 

Suhgrade of Macadam, — The surface upon 
which the broken stone is to be placed must be 
hard, smooth and carefully crowned. This is 
necessary to prevent excessive use of stone on 
the one hand, or the undue waste of stone on the 
other. If the foundation is not hard and firm, 
the stone will be pressed into it by the roller^ 
and thus wasted. If it is not properly crowned, 
an unnecessary quantity of stone will be re- 
quired. "When macadam is to be of uniform 
thickness throughout its cross-section, the crown 
of the subgrade must be the same as that of the 
finished roadway. If the macadam is to be 
thicker at the centre than at the sides, a part 
of the crown will be of the macadam itself, and 
the centre of the subgrade should be raised only 
enough to produce the surface crown when the 



156 EOADS, PATHS AND BRIDGES 

stone is in place. As has already been stated, 
the road machine is a most useful implement in 
shaping the subgrade. 

After the roadbed is shaped to the approxi- 
mate cross-section, it should be rolled until it 
is hard, firm and smooth. If soft places are 
found, or if depressions develop during the roll- 
ing, these should be filled with good material, 
and then further consolidated with the roller 
until the subgrade has the required cross-sec- 
tion as nearly as practicable. 

Placing the Stone. — The stone should be 
placed in courses not to exceed 6 inches in 
depth when loose, as this is about the greatest 
depth which can be thoroughly consolidated 
with a roller. On the prepared subgrade, which 
has been properly rolled and consolidated, is 
spread the first course of stone, usually varying 
in size from 1% inches to 3 inches in the largest 
dimensions. Much larger stone than this 
should not be used in the foundation unless the 
road is to be very thick. In practice two meth- 
ods are used for spreading broken stone. One 
is to dump the stone on a board platform and 
then shovel it into place on the road. The other 



THE BROKEN-STONE ROAD 157 

is to use either an automatic spreader, or else 
dump tlie load directly on the roadway and 
simply spread it by pushing a portion of the 
stone in the different directions, or until the 
required thickness of loose stone is obtained. 
When the stone is spread by simply raking off 
the top of the loads dumped directly on the 
roadway, the proper consolidation is not secured 
by rolling; the stone will be denser and more 
compact where the load is dropped. An uneven 
roadway sometimes results, and in some ex- 
treme cases the position of each load can be 
clearly seen after the road has been in use for 
some time. To obtain the best results each 
load of stone should be dumped in three or four 
piles. This facilitates the spreading and in- 
sures a more uniform distribution of the 
material. 

When about 100 feet or so of the first course 
have been spread, the rolling should begin. The 
roller should commence on the outer edge of 
the macadam with the outer wheel well up on 
the shoulder, and gradually work towards the 
centre of the roadway. When the centre has 
been reached, the road should be crossed over, 



158 EOADS, PATHS AND BRIDGES 

and the other side rolled in the same manner 
as the first. After both sides of the roadway 
are moderately firm, the roller should be moved 
gradually towards the centre, until the entire 
lower course is thoroughly compacted. "Where 
the foundation is poor, or a bad silt soil is 
encountered, it is well to use a filler in the bot- 
tom course. This should consist preferably of 
a good dry sand which is spread over the stone 
after it has been rolled fairly well. The rolling 
is then continued until the voids have been 
forced completely full of sand or stone screen- 
ings. No clay, loam or perishable foreign ma- 
terial should be allowed in the filler. Not only 
will a filler prevent a slippery clay from work- 
ing up into the interstices of the stone, but it 
will also assist in consolidating a stone which 
does not possess good mechanical bonding quali- 
ties, such as quartzite. 

If depressions develop as a result of the roll- 
ing, additional stone of the same size used in 
the course should be added and the rolling con- 
tinued, so that before the second course is 
applied the lower course is smooth and true to 
cross-section. 



THE BEOKEN-STONE EOAD 159 

After about 100 feet of the first course of 
stone is rolled, the second course, consisting of 
stones varying in size from 1% inches down to 
% inch, is spread and rolled in the same manner 
as the lower course. The thickness of the sec- 
ond course usually varies from two to four 
inches compacted. The stone should be care- 
fully spread and considerable vigilance is nec- 
essary if the spreaders are not accustomed to 
their work, in order to prevent the surface hav- 
ing a wavy appearance when the rolling is com- 
pleted. It is quite a temptation with the 
workmen to fill these small depressions with 
screenings rather than with the stones of the 
proper size. 

When the surface is thoroughly compacted, 
which is usually judged by the absence of any 
wavy motion in front of the roller, the screen- 
ings or binder course is applied. Only suffi- 
cient screenings should be applied to fill the 
voids in the stone and form a very slight 
covering on the surface. Screenings should be 
spread in successive thin coats with alternate 
rolling. Sometimes it is a good plan to pass 
the roller once or twice over the screenings 



160 EOADS, PATHS AND BEIDGES 

as they have been spread on the roadway while 
they are dry. The sprinkler is then put on in 
advance of the roller, and as much as possible 
of this dust of the screenings is flushed into the 
crevices of the stones. The sprinkling and roll- 
ing should continue until the surface puddles, 
showing that the voids are substantially filled. 
The process of binding the top course is the 
most critical one of the entire job. The ability 
of the roller operator is a very important factor 
in macadam work. The appearance of the road 
surface depends to a large extent on his skill. 
As soon as the road has been puddled, it 
should be allowed to dry a few days, and may 
then be opened to traffic. In fact, if a road can 
be opened in sections as completed, it is more 
preferable than to wait until the entire road is 
done, and then throw it open. Where it is 
opened in sections, it will be found possible at 
times to run back over it with the sprinkler and 
roller. Traffic on a green road always produces 
more or less roughness or even ravelling, so that 
permitting travel on the road while it can still 
occasionally be reached with the roller, is one 



THE BEOKEN-STONE EOAD 161 

of the most rapid ways of obtaining the final 
set to the road. 

On a very clayey or silty soil considerable 
care must be exercised in order to prevent the 
water from reaching the subgrade in quanti- 
ties sufficient to soften it. If much water 
reaches the subgrade, there is great danger that 
the clay will be forced up into the stone, and 
depressions will result, and the undesirable clay 
will penetrate into the stones. 

Cost of Macadam, — No formula has yet been 
devised whereby the cost of macadam roads can 
be computed for any locality without a detailed 
survey and close examination of conditions. 
There are too many uncertain factors which 
enter into the construction of the road in such 
varying proportions to make a table of cost 
of macadam roads of any great practical value. 
Each road is a problem in itself, and while one 
mile of road may cost a given amount, the 
adjoining mile may often cost twice as much, 
for no other reason than the variation of neces- 
sary factors. Eoughly, it may be stated that in 
various parts of the United States the cost of 



162 EOADS, PATHS AND BBIDGES 

macadam roads, having a width of 15 feet and 
a thickness of seven or eight inches, ranges 
from $2,000 to $10,000 per mile. 



CHAPTER VIII 

SELECTION OF MATERIALS FOR MAC- 
ADAM ROADS 

It is impossible to construct a satisfactory 
macadam road with inferior materials. If a 
very soft rock is used, the road will wear rapidly 
and soon have to be renewed. If the rock does 
not possess sufficient binding power and no ade- 
quate binder is used, it will not consolidate, and 
the road will soon go to pieces. Enormous 
sums of money have been wasted through the 
use of unsuitable materials, and there are many 
examples of unnecessary expense through the 
use of material brought from a long distance 
when one locally available would have answered 
the purpose equally well. 

It has been found that, in a general way, 
certain classes and types of rock are more suit- 
able than others for road building. For 
example, trap rock is considered to be an 
excellent material for macadam roads, while 

163 



164 ROADS, PATHS AND BRIDGES 

quartzite is of very little value except in the 
foundation. Unfortunately, the trap stones 
are not common to all sections of the United 
States. Some of the fine-grained granites 
usually give good results, as do the felsites, 
some of the harder limestones and the dolo- 
mites. 

In general the micaceous, schistose and meta- 
morphic rocks have but little value as sur- 
facing material. Sometimes, however, the 
harder of these may be used for the lower 
course of the macadam, while the upper 
course is built of a better grade of stone. 
Some of the coarsely crystalline granites and 
some of the limestones, if very soft or if crys- 
talline to any extent, are of very little value. 
On the other hand, however, there are instances 
recorded where certain schistose rocks have 
been used with excellent results. The following 
table gives in compact form the classification 
of all rocks used in the construction of macadam 
roads : 



SELECTION OF MATEEIALS 165 



GENEKAL CLASSIFICATION OF EOCKS. 



Class. 



I. Igneous. 



Type. 



Intrusive 
(plutonic) 



Extrusive . 
(volcanic) 



Family. 

' a. Granite 

b. Syenite 

c. Diorite 

d. Gabbro 
^e, Peridotite 

a. Rhyolite 

b. Trachyte 

c. Andesite 

d. Basalt and 
-L base 



dia- 



II. Sedimentary 



Calcareous { ^- Limestone 

l b. Dolomite 



2. Siliceous 



a. Shale 
Sandstone 
Chert (flint) 



m. Metamorphic 



1. Foliated 



{!: 



Gneiss 
Schist 
Amphibolite 



ra. Slate 

2. Nonfoliated J ^- Quartzite 

I c. Eclogite 
L d. Marble 



Igneous or fire-formed rocks are those which 
at one time have been in a molten state and have 
solidified, either underground or on the earth's 
surface. Heat, pressure, and the chemical 
composition of the rock, together with the pres- 
ence of vapours, were the causes which gov- 
erned the final structure of the material. 
Those rocks which were consolidated deep 
underground are known as plutonic and are 
formed of coarse crystals. Examples of plu- 
tonic rocks are granite, syenite, and diorite. 



166 EOADS, PATHS AND BEIDGES 

The rocks wliicli have solidified at the surface 
include rhyolite, andesite, and basalt. The 
colour of igneous rocks varies from light 
grey, pink and brown to dark steel grey or 
black. The dark varieties are generally called 
trap, a term derived from trappa, a Swedish 
word meaning stair, as the formation frequently 
resembles stairs. 

Sedimentary rocks are composed of fine rock 
particles and fragments which have been pro- 
duced by the disintegration of rocks of various 
types, carried by running water and deposited 
in layers on sea or lake bottoms. Examples of 
sedimentary rocks are limestone, sandstone and 
shale. 

Metamorphic rocks are those which have been 
formed by the action of chemical or physical 
forces on igneous and sedimentary rocks. Ex- 
amples of this class are gneiss, slate, quartzite 
and marble. 

As far as it is possible to determine the rela- 
tive value of the various rocks for road building 
according to their mineral classification, it may 
be said that the following is the order in which 
they should be ranked: 



SELECTION OF MATERIALS 167 

1. Trap. 

2. Syenite. 

3. Non-crystalline Limestone. 

4. Chert. 

5. Granite. 

6. Mica Schist. 

7. Quartzite. 

Stone from a ledge, because of its uniformity, 
is usually ^better than field stones, but if the 
ledge is of an inferior grade of rock it should 
not be used merely because it is ledge stone, 
in preference to field stones of better quality. 
The aim in the selection of a road material 
should always be to get a rock of uniform qual- 
ity. Badly weathered stone from the surface 
or outcrop of a ledge should never be mixed 
indiscriminately with the fresh stone from the 
interior. 

Physical Qualities, — The mineral classifica- 
tion of rocks is by no means a conclusive test 
of their fitness for road building, as there is a 
wide variation in the qualities of different out- 
crops and deposits of materials belonging to the 
same class and type. 

It is the aim of the road builder to obtain a 
road with a surface as nearly smooth as pos- 



168 EOADS, PATHS AND BEIDGES 

sible, not too hard, too slippery, or too noisy, 
and which will be as free as possible from mud 
and dust. These results are to be obtained and 
maintained at as small a cost as possible. In 
order to produce even approximately such con- 
ditions, it is necessary that only rock possessing 
certain essential physical qualities, irrespective 
of mineral properties, be used. 

In order to determine what qualities are 
essential in a road material, it must be borne 
in mind that the road will be called upon to 
withstand the wearing action of wheels and 
horses' hoofs, as well as the action of the ele- 
ments, in the form of rain, wind and frost. 

Hardness is the quality possessed by rock 
which enables it to resist the wearing action of 
the wheels and horses ' hoofs. It is evident that 
hardness is an essential quality, and particu- 
larly so if the road is heavily travelled. 

Toughness is that quality in the rock by which 
adhesion between the crystalline and fine par- 
ticles of the rock is so great as to give it 
power to resist fracture when submitted to the 
blows of traffic. Its quality is different from 
hardness. The difference is illustrated by the 



SELECTION OF MATERIALS 169 

statement that the resistance by rock to the 
grinding of an emery wheel would be consid- 
ered hardness, while the resistance to fracture 
when the rock is struck by a hammer is tough- 
ness. 

A third and very important quality in road 
material is the cementing or binding poiver, 
which is the property possessed by rock dust 
to form a cement or bond when wet, whereby 
the coarser fragments of the surface course are 
bound together and the whole forms a smooth, 
water-proof shell or crust. Since it is abso- 
lutely necessary to protect the subgrade from 
water, it will readily be seen that the rock which 
does not possess sufficient binding power is 
likely to form a loose surface, which will permit 
the water to sink through and soften the sub- 
grade or foundation, thereby destroying the 
stability of the whole road. 

It is important in the selection of material 
for a macadam road to consider the character 
of traffic which the road will be called upon to 
sustain. To make this point clear, the theory 
upon which the macadam road rests may be 
again explained as follows : The rock dust which 



170 EOADS, PATHS AND BRIDGES 




Cross Section, Roman Road (Appian Way). 




Cross Section, French Road (Roman Method), 
previous to 1775. 




Cross Section, Tresaguet Road, 1775. 




Cross Section, Telford Road, 1820. 




Cross Section, Macadam Road, 1816. 




Cross Section of Modem Macadam (Massachusetts) Road 
with V-shaped foundation. 




Cross Section of Modem Macadam Road. 



SELECTION OF MATERIALS 171 

fills the voids between the angular fragments of 
stone and forms a cement or binding material 
when wet is gradually carried away by wind, 
rain and the action of traffic. It is known, 
however, that the hoofs of the horses and the 
iron-tired wheels of vehicles wear a sufficient 
amount of new dust from the fragments of rock 
to replace -that which is lost in this manner. 
Consequently, the bond of the road is automatic- 
ally renewed. If, therefore, a very hard rock 
is used in the construction of a macadam road, 
heavy traffic will be necessary in order that 
there may be sufficient wear to produce the 
essential rock dust. If, on the other hand, a 
soft material is used for a heavy traffic road, 
the rock will be worn away far more rapidly 
than is necessary for the automatic binding of 
the road. Practical road builders realise that 
for very heavily trafficked roads a hard ma- 
terial, such as trap rock, is essential, and that 
for light trafficked roads limestone or other ma- 
terial which is not as hard as trap rock will 
serve every purpose. 

An important series of experiments con- 
ducted by the United States Office of Public 



172 EOADS, PATHS AND BRIDGES 

Roads developed the fact that the addition of 
limestone screenings to hard material, such as 
granite or diabase, increases the cementing 
quality to a marked degree. The experiments 
were carried still further and lime water was 
mixed with the granite. The tests showed in 
every case a marked increase in the cementing 
value of the granites treated, and the inference 
is that the addition of lime will greatly in- 
crease the binding power of certain road-build- 
ing rocks. As a result of these experiments, 
the conclusion was reached that mixtures of 
acid and basic rocks give a higher cementing 
value than either rock alone. 

To enable the road builder to determine the 
value of a rock as a road material, a number of 
tests have been devised. These tests, however, 
require special apparatus, and much skill and 
good judgment on the part of the operator. 
The Office of Public Roads of the United States 
Department of Agriculture maintains a splen- 
didly equipped laboratory where tests and an- 
alyses of rocks are made free of charge. No 
construction of any importance should ever be 
undertaken without having the rock tested, un- 



SELECTION OF MATEEIALS 173 

less it has already been subjected to that best 
of all tests, actual use on the road for a number 
of years. 

Directions are issued by the United States 
Office of Public Eoads for the selection and 
shipment of specimens of road material for 
laboratory tests, and if followed carefully, the 
selection of the best available material should 
be insured. In order to have road materials 
tested in the laboratory of the Office of Public 
Eoads, the instructions below must be carefully 
followed : 

1. All samples should be selected to represent as 
nearly as possible an average of the material. 

2. A sample of rock for laboratory tests must con- 
sist of stones which will pass through a three-inch 
but not through an inch and a half ring — excepting 
one piece, which should measure, approximately, four 
by six inches on one face and be about three inches 
thick. The whole sample should weigh not less than 
thirty pounds. It is desired that samples of rock be 
shipped in burlap bags. 

3. A sample of gravel must weigh not less than 
twenty-five pounds, and should not contain stones 
over one inch in diameter. Such samples must be 
shipped in boxes, sufficiently tight to prevent the 
finer material from sifting out. 



174 EOADS, PATHS AND BRIDGES 

4. A blank form and addressed tag-envelope will 
be supplied by the Office for each sample. The blank 
form must be filled and placed in the tag-envelope, 
which must be used as the address for the sample. 
It is essential that the blank form be filled with the 
utmost care, as they are filed as records of the samples. 

5. The Office desires to keep a record of the actual 
wear on roads built of the materials tested. If the 
material which this sample represents has been or is 
about to be used on roads, this Office would desire 
to be informed of the addresses of those in charge of 
the construction and maintenance of such roads. 

6. Samples must be shipped, freight or expressage 
PREPAID, and bills of lading or express receipts 
forwarded by mail to the Office of Public Roads, De- 
partment of Agriculture, Washington, D. C. 

7. The Office makes no charge for tests. 

Distribution of Road Materials. Trap RocJc, 
— Trap rock is abundant tbroughout the most 
of New England, except in the northern part 
of Maine. The best quality is found in the 
valley of the Connecticut, south of the Vermont 
and New Hampshire line, and along the coast 
between Boston and Eastport, Me. Excellent 
trap is found in the upland portion of New 
Jersey and in parts of Maryland and Pennsyl- 
vania. New York is not so well supplied except 
along the Hudson in the vicinity of the Pali- 



SELECTION OF MATERIALS 175 

sades. South of the Potomac River trap rock 
is limited to the Blue Ridge Mountains and to 
the Piedmont country east of the Appalachian 
Mountains. In the country between the Appa- 
lachian Mountains and the Mississippi River, 
very few trap dykes occur. The northern part 
of Michigan is abundantly supplied with trap 
rock. West of the Mississippi, in southern Mis- 
souri, Arkansas and Oklahoma, there are a few 
scattered rocks of this nature, but in the Rocky 
Mountains, and on the Pacific Coast, excellent 
trap rock abounds. 

Granitic Roclcs, — Granitic rocks, which in- 
clude granites, syenites, and the harder gneiss, 
follow in general the same distribution as the 
trap rocks, and it is said that between the traps 
and granites about one-third of the area of the 
United States is well supplied with road-build- 
ing stone. 

Quartzites, — The quartzites are found partic- 
ularly in the mountainous districts of the Appa- 
lachian and Cordilleran regions, and in the 
Ozarks and Adirondacks. 

Limestones. — Limestone is found in many 
parts of the Mississippi Valley, in the southern 



176 EOADS, PATHS AND BEIDGES 

parts of Indiana, Ohio, tlie Valley of Virginia, 
in Kentucky, eastern Tennessee, and northern 
Alabama. 



CHAPTER IX 
MAINTENANCE AND REPAIR 

The terms maintenance and repair are very 
frequently used as synonyms, but there is a wide 
distinction between the two operations. To 
maintain a road means to keep it always in good 
condition, while to repair a road means to make 
it good only occasionally. In other words, 
repair sets in after maintenance fails to keep 
the road in proper condition. To maintain a 
road, therefore, means not to let it become bad ; 
to repair it, means to improve it after it has be- 
come bad. 

There is no phase of the subject of road im- 
provement so important, and which is so often 
neglected, as that of maintenance. Roads may 
be constructed in a most scientific manner, and 
out of the best materials available, but unless 
they are properly maintained, they will sooner 
or later go to pieces. On the other hand, roads 
may be very poor, but with systematic main- 

177 



178 EOADS, PATHS AND BEIDGES 

tenance and repair, they may be rendered 
passable at all seasons of the year for ordinary 
traffic. No road bas ever been so well con- 
structed that it did not need to be maintained. 
Even tlie tremendously massive roads of the 
Eomans have almost disappeared owing to this 
lack. 

It has been the universal practice in America 
to repair the roads at such times as will inter- 
fere least with individual duties, and this has 
crystallised into repairing the roads once or 
twice a year. So hard and fast has this custom 
become in many of the States that, even if costly 
macadam roads are constructed at great ex- 
pense, they are allowed to go to ruin because 
minor defects are permitted to go unrepaired 
until they result in practical destruction of the 
road. 

A 'road is no more than completed before 
the destructive forces set in. These destruc- 
tive agencies are largely due to traffic and 
the elements. They act and react upon 
each other in such manner as to make the 
determination of the wear due to each a very 
difficult matter. It has been estimated that 



MAINTENANCE AND EEPAIR 179 

ordinarily about 80 per cent, is due to traffic 
and 20 per cent, to weathering. Of the former 
about 56 per cent, is believed to be due to the 
effects of the horses' feet, especially the calks, 
and 44 per cent, due to the abrasion of the 
wheels. Ordinarily the forces of destruction 
may be given in the order of their importance, 
as the shoes of the horses, the wheels of the 
vehicles, and the weather. 

Even the most superficial examination of our 
roads tells us that the wear on our highways 
is no negligible amount. The hardest rock will 
wear, and the most important road problem 
before highway engineers to-day is one of road 
maintenance, rather than of road construction. 
It is worse than folly to build expensive roads 
and then expect them to take care of themselves. 
Not a few States are awakening to the sad reali- 
sation, hastened, to be sure, by the automobile, 
that even State-aid roads must be maintained 
after they are built. 

No more admirable system of maintenance 
could be devised than that which is followed in 
France. Every mile of road is inspected daily, 
and the slightest defect is mended at its incep- 



180 EOADS, PATHS AND BEIDGES 

tion. The maintenance-of-way departments of 
our great railroad systems do not provide a 
more thorough inspection of railroad tracks 
than do the French for their public roads. The 
changes which should come in the American 
system will mean the adoption of a continuous 
system of repair and a methodical inspection of 
all roads. 

American Methods of Maintenance. — There 
are three systems of road maintenance in use 
in this country, viz.: the contract system, the 
labour-tax or personal-service system, and the 
system which provides men permanently em- 
ployed to look after particular sections of road. 

The contract system has been used to some 
extent in various States, but it has never been 
found entirely satisfactory. As a general rule, 
the amount paid for this work is small and such 
poor service is rendered that in many cases the 
roads have become worse rather than better. 
Some of the European countries adopted it dur- 
ing the last century, but the experiment proved 
a failure. 

The working out of personal or property taxes 
upon the public roads has never proved satis- 












EFFECT OF TREATMENT WITH A SPLIT-LOG DRAG, 
A rnad in Iowa before and after dragging. 



MAINTENANCE AND EEPAIE 181 

factory. No State or community has ever built 
or kept in repair a system of first-class im- 
proved roads under the personal-service or 
labour-tax system. In fact, this system is not 
applicable even to earth roads. Its principles 
are unsound, its operations unjust, its practice 
wasteful, and the results obtained under it are 
unsatisfactory in every particular. 

Undoubtedly the best system of maintenance 
is that which provides for the permanent em- 
ployment of skilled labourers or caretakers, who 
may have charge of particular sections of road 
or who may be assigned to any part of a county 
or district where the work is most needed. 
Men employed in this way become experts in 
their particular line of work, and if they make 
mistakes one year, they are pretty apt to correct 
them the next ; but, under the labour-tax system, 
these mistakes are repeated continuously. If 
one man is employed to look after a particular 
stretch of road, or to do a particular class of 
work, he will soon learn to take pride and in- 
terest in his work. 

This system has been adopted in this coun- 
try only to a limited extent. It has been used 



182 EOADS, PATHS AND BRIDGES 

by the Massachusetts Highway Commission for 
several years. The New York State Highway 
Commission introduced it in the year 1910 for 
the maintenance of State roads, and Allegheny 
County, Pennsylvania, employs it for the main- 
tenance of about 100 miles of county roads. 

While it would be manifestly impossible to 
adopt this system throughout the entire country 
on account of limited resources and sparse pop- 
ulation, still it is believed that there are many 
places where it might be used with great suc- 
cess. It would be difficult to find a county 
which is so poor that it could not afford to em- 
ploy continuously eight or ten labourers and 
three or four teams to maintain and repair its 
roads; and many counties could well afford to 
employ ten times such a force. That such a 
plan would be more effective than either the 
labour-tax or the contract system would appear 
to be self-evident. 

Neglect of Earth Roads, — Of all our roads, 
the earth roads are probably the most neg- 
lected. Experience has shown that by proper 
maintenance a well-constructed earth road can 
be transformed into something better than 



MAINTENANCE AND EEPAIR 183 

elongated mud-holes. The first and last com- 
mandment in the maintenance of earth roads is 
to keep the surface well drained. Water is the 
great enemy to our clay and heavy-soil earth 
roads, and must be removed immediately, or 
much mud is the result. To insure good drain- 
age, the ditches must be looked to and obstruc- 
tions removed, and the smooth, raised crown of 
the road maintained. For this purpose the 
split-log drag, or some similar device, is very 
useful, and at the same time inexpensive. 

The drag should be used while the road is wet 
from recent rain and while the clay is plastic 
and too wet for the use of a road machine, but 
not in such a state as to adhere very much to the 
drag. The theory of the drag is simply this: 
Most clays and heavy soils will puddle and set 
very hard. The drag is essentially a puddling 
machine, and hence must be used while the 
earth contains enough moisture to puddle. The 
drag should be driven up one side of the road 
and down the other, inclined at an angle of 
about 45 degrees to the line of the road, so that 
a little earth is always moved toward the centre. 
In this way, the crown will be maintained, ruts 



184 EOADS, PATHS AND BRIDGES 

and depressions filled, and the entire surface 
plastered over with a thin coat of puddled clay 
or earth, which packs very hard under passing 
traffic. The drying action of the sun and wind 
bakes the surface into a hard crust. Continued 
use of the drag will soon cause the road to be 
literally shingled over with successive layers of 
puddled earth as hard and dense as earth can 
be made without costly treatment. 

The following points should be borne in mind 
in dragging a road: ^ 

1. Make a light drag which is hauled over the 
road at an angle so that only a small amount of earth 
is pushed to the centre of the road. 

2. Eide on the drag and never drive faster than a 
walk. 

3. Begin on one side of the road or wheel track, 
returning on the opposite side. 

4. Drag the road as soon as possible after every 
long wet spell, when the mud is in such a condition 
as to puddle well and still not adhere too much to 
the drag. A few draggings on any given road will 
give the operator a clue to the proper way and best 
time to drag. 

5. Drag at all seasons of the year, but do not drag 
a dry road. If a road is dragged immediately before 
a cold spell, the road will freeze in a smooth condi- 



MAINTENANCE AND EEPAIR 185 

tion and do away with our extremely rough winter 
roads. 

6. Always drag a little earth toward the centre, 
with the aim of keeping the slope of the crown from 
34 inch to 1 inch to the foot. If the drag cuts too 
much, shorten the hitch or change your position on 
the drag. 

The best results from dragging are obtained 
only by repeated applications. One or two an- 
nually will not maintain an earth road in its 
best condition, unless the traffic is light. Some 
gravel roads may be considerably improved by 
dragging, especially if the gravel contains any 
clay, but it will do no good on a well-bonded 
macadam road. 

The Sand-Clay Road, — The best method of 
maintaining a sand-clay road is by means of a 
split-log drag or a reversible road grader. The 
small ruts and depressions which are liable to 
form undei* heavy traffic, particularly in wet 
weather, should be filled as soon as possible 
after they are formed; otherwise the traffic is 
liable to cut through the sand-clay surface and 
destroy whole sections of the road, making it 
necessary to resurface it. The drag or road 
machine should be used in damp weather so that 



186 EOADS, PATHS AND BEIDGES 

the surface will pack and bake while the road is 
drying out. 

If the surface becomes loose in dry weather, 
this is an indication that there is not enough 
clay in the mixture. This defect may usually 
be remedied by a thin application of clay, raked 
in with a tooth harrow or worked in by means 
of a disc harrow. The mixing should be done 
in damp weather, and just before the road dries 
out it should be scraped with a reversible 
grader or a split-log drag. 

If the road becomes sticky or muddy in wet 
weather, this indicates that there is not enough 
sand in the mixture. A thin layer of sand ap- 
plied in wet weather will usually remedy this de- 
fect. The sand can ordinarily be worked into 
the surface by traffic, although quicker results 
can be obtained by *^ discing'' or harrowing. 
Small holes and depressions in the surface may 
be remedied usually by the application of a 
small quantity of sand and clay of the proper 
mixture raked into position with a garden rake. 
These patches should be carefully made so that 
when they finally consolidate, the surface will 
be smooth and free from bumps or depressions. 



MAINTENANCE AND EEPAIR 187 

Care of Gravel Roads. — A gravel road re- 
quires more attention the first year after its 
construction than for many years thereafter. 
Small ruts and depressions should be filled as 
soon after they are formed as possible; other- 
wise, they will catch water, which soaks through 
to the foundation, softens the subgrade, and 
causes the whole surface to wear rapidly or to 
give way entirely. A small quantity of mate- 
rial will fill incipient ruts and holes, but if neg- 
lected, a cartload of material may be required 
to repair a hole, which might otherwise have 
been filled by a shovelful. 

Small depressions may be filled by adding 
fresh gravel, but, as a general rule, all that is 
needed is to rake the loose gravel from the side 
of the road into them. A split-log drag or 
some similar device is very useful for this pur- 
pose. If fresh gravel is added, all coarse mate- 
rial should be eliminated and the gravel should 
contain enough fine material to cement it to- 
gether. A little clay is sometimes helpful, but 
too much clay will render the road dusty in 
summer and muddy in winter. 

A gravel road should not be considered fin- 



188 ROADS, PATHS AND BRIDGES 

islied until it has been in use for at least one 
year. If the road has been properly main- 
tained, it will be found, after about a year's 
service, that the wheels of heavily loaded wag- 
ons wiU not form ruts or depressions in the 
surface. The road will require but little at- 
tention for several years after it has passed 
through this formative period. Attention 
should still be given, however, to the side 
ditches and to culverts. They should be kept 
open and free, so as to permit water to drain 
quickly away from the road, especially during 
the spring of the year, when the snow and ice 
are melting. After a few years it will be found 
that the gravel will work toward the sides of the 
road, leaving a depression in the centre, which 
will prevent or interfere with the flow of the 
water from the surface to the side ditches. 
This will not be the case, however, if the road is 
dragged with a split-log drag, or surfaced from 
time to time with a reversible grader. 

.If the reversible grader is used for this pur- 
pose, care should be taken not to shove earth, 
sods, or weeds from the side ditches to the cen- 
tre of the road, or if this is done, then such trash 




GOOD AND BAD MAINTENANCE. 

1. (Top.) A French highway and one of its caretaking patrolmen. 
2. An American example of worn-out macadam. 3, Rude road-mend- 
ing in the southern United States. 



MAINTENANCE AND EEPAIR 189 

should be, by all means, removed. Hundreds 
of miles of fairly good gravel roads are seri- 
ously injured every year by this practice of pil- 
ing sods and trash in the centre. 




The Split-log Drag 



The best time to use the drag or road machine 
on a gravel road is just after a heavy rain, 
when the surface is comparatively soft and 
when the material which is scraped towards the 
centre will pack again into a hard crust. This 
work should never be done in dry weather, for 
the reason that the loose material will soon turn 
to dust or mud. 

The crown of the average gravel road should 
be maintained at about an inch or three-quar- 



190 EOADS, PATHS AND BRIDGES 

ters of an inch to the foot. That is, a road 
which is 18 feet wide from shoulder to shoulder 
should have a crown of not less than 6 inches 
nor more than 9 inches. If the crown be 
greater than 9 inches, the traffic will be forced 
to use the centre of the road, which will soon 
cause ruts or depressions to form in the surface. 
If the crown is less than 6 inches, the surface 
will not properly drain itself. By making the 
slope about three-quarters of an inch to the 
foot, it will be found that the traffic will use the 
whole surface of the road and will, in that way, 
distribute the wear much better than with a 
higher crown. 

If gravel roads are neglected, especially 
while they are new, they will soon go to pieces 
and the money and labour expended upon them 
will be wasted. Constant attention should be 
the watchword. If it is estimated that a 5-mile 
stretch of road will require a hundred days' 
labour each year to keep it in repair, then it is 
much better to distribute that labour through- 
out the year than to have the work done all at 
one time. One man can do better work in main- 
taining a gravel road by working 313 days an- 



MAINTENANCE AND EEPAIE 191 

nually than 313 men can in working one day 
annually. The old adage, '*A stitch in time 
saves nine," applies with equal force to the 
maintenance of a gravel road. 

Even though a gravel road may be main- 
tained in good condition, it will require resur- 
facing from time to time, especially if the road 
is heavily travelled, or if the material is poor. 
For this repair work the very best gravel avail- 
able should be used, and the work should, if 
possible, be done when the ground is damp, so 
that the new material will knit and bond itself 
to the old road surface. 

It is the usual custom in many communities 
in repairing an old gravel road to dump 
wagon-load after wagon-load of material in a 
windrow in the middle of the road, and then to 
leave it in that condition to be spread by the 
traffic. This practice cannot be too severely 
condemned. These large piles of gravel in the 
middle of the road are dangerous, especially at 
night to those travelling in buggies or automo- 
biles, and many serious accidents are due to 
this cause. The material if piled up in this way 
is gradually pushed by the traffic towards the 



192 EOADS, PATHS AND BEIDGES 

side ditches, and by the time the road is con- 
solidated, at least 50 per cent, of the gravel is 
wasted by being ground and pounded by the 
wheels of vehicles, the hoofs of horses and the 
tires of automobiles. Even after the road is 
consolidated, the surface is full of bumps and 
holes, which render it disagreeable to travel 
and difficult to maintain. 

The best practice in repairing is to dump 
each load of gravel in three or four places and 
then to pull the material into position with a 
garden or other suitable rake, eliminating all 
pebbles larger than two inches in diameter. 
Another good practice is to spread the material 
over the surface with a reversible grader and 
then rake it with a tooth harrow. In no case, 
should the load from one wagon be dumped in 
one place, as this produces a bumpy surface. 

The repairing should by all means be under- 
taken in the spring of the year, so that the 
gravel will have time to consolidate before dry 
weather sets in. If the gravel is spread in the 
summer or early fall, it will remain loose until 
the winter rains come. The water will then 
penetrate to the foundation, rendering it so soft 



MAINTENANCE AND REPAIR 193 

that mncli of the gravel will disappear during 
the ensuing winter. 

Where extensive repairs are to be made, a 
steam roller with spiked wheels may be used to 
good advantage in tearing up the old roadbed. 
A tooth harrow may then be drawn over the 
surface, which will permit the dirt, clay and 
sand to sift to the bottom and will bring the 
loose gravel to the surface. The road may then 
be rolled, and a layer of suitable binding gravel 
applied, after which it should be sprinkled and 
again rolled until it is ready for traffic. The 
roller and sprinkler will not be needed if the 
materials pack well under traffic, although bet- 
ter results can usually be obtained by their use. 

Some gravel roads may be considerably im- 
proved by surfacing them with a thin layer of 
hard, tough rock screenings, such as the traps 
and better grades of granite. This method has 
been pursued for parks and boulevard roads in 
the District of Columbia. A large mileage of 
gravel roads has been surfaced with trap-rock 
screenings. These roads have the appearance 
of macadam and wear practically as well, and 
at the same time are much cheaper than if they 



194 EOADS, PATHS AND BEIDGES 

were built entirely of broken stone. Some of 
them have been oiled recently and with very 
gratifying results. 

Maintaining Macadam Roads. — The causes 
of wear on macadam roads are the weather, the 
wheels of vehicles and the hoofs of horses. The 
weather acts to some extent directly on the 
materials, but to a much greater degree indi- 
rectly. Frost is one of the most active of these 
agencies. The expansion and contraction 
caused by frost leads to a general disintegra- 
tion of the road surface. This is especially 
true where much clay was allowed in the binder, 
where the road surface was porous or the drain- 
age poor. When such a road thaws out after 
a hard freeze, the macadam will practically be 
a layer of loose stones into which the traffic will 
cut, forming ruts. Eain, following a frost and 
thaw, is especially damaging, and a series of 
thaws, rains and frosts, will entirely destroy 
the bond in a road when once the water has 
gained access into the stone. Frost has but 
little, if any, effect on a dry, well-kept road. 
The solution is self-evident. Look after the 
drainage very carefully in the fall and be sure 



MAINTENANCE AND EEPAIR 195 

that the surface is as nearly waterproof as pos- 
sible, so that the road will, at the beginning of 
winter, be dry and not full of water. Violent 
rains on exposed localities wash out the binder, 
and sometimes the smaller stones as well, leav- 
ing the surface both rough and porous. Over- 
flows from blocked gutters or choked cross- 
drains cause much damage in the same way. 
The amount of material lost from the roads by 
this means is often larger than the toll exacted 
by traffic. 

If an excess of water is detrimental to a road, 
however, an extended drought is little or no 
better. The winds remove the binding mate- 
rial both by blowing it directly from the surface 
of the road and by carrying off the dust raised 
by traffic. This causes the road to '^ ravel.'' 
These loose stones should be removed, as leav- 
ing them on the road not only makes traffic dis- 
agreeable, but also tends to loosen still others. 
The stones which are picked off the road will 
rarely prove of value for repair work, as they 
are too much rounded to bond readily. 

The wheels of passing vehicles produce on 
the road several effects, which should be 



196 EOADS, PATHS AND BRIDGES 

understood. First, there is the grinding and 
crushing action on the surface, and second, the 
pressure throughout the entire body of the road 
covering. If for any reason the materials are 
not thoroughly consolidated, there is a third 
action of displacement accompanied by internal 
wear as the stones rub against each other. If 
the road surface is hard, smooth and water- 
proof, the wear will be the least possible and 
will be confined to the surface. The aim should, 
therefore, be directed toward a constant main- 
tenance of a hard, smooth, waterproof surface. 
The actual amount of wear on any given road 
surface depends on several conditions, viz., the 
amount and kind of traffic, climate and other 
local conditions, and the kind of road material 
used. Generally speaking, however, the amount 
of wear is less in proportion as the road is kept 
in good condition as to surface, solidity, and 
drainage. It is usually less on slight grades 
than on dead level, because of the better drain- 
age, but on steep hills it is increased by the 
effects of running water. Strange to say a hill 
usually looks better after a heavy rain than the 
flat below. This is because the hill is washed 



MAINTENANCE AND EEPAIE 197 

clean, while the flat is more or less covered with 
the debris and mud carried down from above. 
This often leads to a neglect of the hills until 
they are so badly worn as to require resurfac- 
ing. 

The amount of maintenance required will 
vary with the season and the local conditions. 
Ordinarily there is more wear in winter than 
summer, and more in wet places than in dry. 
The reverse, however, is true on roads with 
heavy automobile traffic, when dry weather 
proves especially injurious. 

The amount of wear is also greatly aug- 
mented by the prevailing tendency of the traffic 
to follow in the same track, especially where 
the surface is soft, so that the tracks become 
visible. In parts of Germany the road labour- 
ers have a custom of placing large stones on to 
the road whenever a rut or depression tends to 
form, because of the concentration of the traffic 
along this one line. The stones serve to deflect 
the traffic and so keep the wear uniformly dis- 
tributed over the entire road surface. 

Proper maintenance consists in replacing the 
materials lost by unequal wear, so that the road 



198 KOADS, PATHS AND BRIDGES 

is always in a good smooth condition. In mak- 
ing repairs, the materials should be spread only 
on the places which require them. Thus no por- 
tion of the surface is neglected, and no mate- 
rials are wastefully applied to portions already 
thick enough to stand the traffic. Uniformity 
in both strength and smoothness with the least 
use of materials and least cost is the thing to 
be sought. In spreading new stone, the old 
method of waiting until the road has entirely 
lost its shape and then spreading a thick coat 
which is left to be worked in wholly by the 
traffic cannot be too severely condemned. This 
method is very wasteful of material, as well as 
extremely inconvenient to traffic. A great deal 
of the material is ground up and crushed be- 
fore it is consolidated, and even after consolida- 
tion the surface is rarely if ever left smooth. 
The materials necessary to replace the loss by 
wear of ordinary traffic should be spread in 
comparatively small quantities where hollows 
or weak places occur, or where required to keep 
the cross section of the road in proper form. 
If laid in with care and in small patches, the 
inconvenience to traffic will scarcely be notice- 



MAINTENANCE AND EEPAIE 199 

able. If the task of consolidating the materials 
laid is to be left to the public, it is only proper 
that they should demand that the process be 
made as easy and speedy as possible, which is 
readily attained by good arrangement and care 
in spreading the materials, and close atten- 
tion afterwards until they are consolidated. 
Where, because of neglect, or other reasons, it 
is necessary to make extensive repairs or re- 
surfacing, the steam roller should always be 
employed to do the consolidation. Especially 
is this true if the road is extensively used by 
automobiles. 

The steam roller is also a very useful machine 
in the maintenance of roads softened by winter 
frosts. A few trips in the spring of the year 
soon after the frost has left the ground will 
remove the slight ruts beginning to form, and 
recompact the road's surface, rendering it hard, 
smooth and waterproof. All loose stones 
should be removed before the road is rolled. 

The following instructions to road men, is- 
sued by The Eoad Improvement Association of 
London, should be found useful in the mainte- 
nance and repair of macadam roads : 



200 ROADS, PATHS AND BRIDGES 

1. Never allow a hollow, a rut, or a puddle to re- 
main on a road, but fill it up at once with chips from 
the stone-heap. 

2. Always use chips for patching, and for all re- 
pairs during the summer months. 

3. Never put fresh stones on the road, if by cross- 
picking and a thorough use of the rake the surface 
can be made smooth and kept at the proper strength 
and section. 

4. Remember that the rake is the most useful tool 
in your collection, and that it should be kept close at 
hand the whole year round. 

5. Do not spread large patches of stone over the 
whole width of the road, but coat the middle or horse 
track first, and when this has worn in, coat each of 
the sides in turn. 

6. Always arrange that the bulk of the stones may 
be laid down before Christmas. 

7. In moderately dry weather and on hard roads, 
always pick up the old surface into ridges six inches 
apart, and remove all large and projecting stones be- 
fore applying a new coating. 

8. Never spread stones more than one stone deep, 
but add a second layer when the first has worn in, 
if one coat be not enough. 

9. Use a steel-pronged fork to load the materials 
at the stone-heap, so that the siftings may be avail- 
able for "binding" and for summer repairs. 

10. Go over the whole of the new coating every 
day or two with the rake, and never leave the stones 
in ridges. 



MAINTENANCE AND EEPAIE 201 

11. Kemove all large stones, blocks of wood, and 
other obstructions (used for diverting the traffic) at 
nightfall, or the consequences may be serious. 

12. Never put a stone upon the road for repairing 
purposes that will not pass freely in every direction 
through a 2-inch ring and remember that still smaller 
stones should be used for patching and for all slight 
repairs. 

13. Eecollect that hard stone should be broken to a 
finer gauge than soft, but that the 2-inch gauge is the 
largest that should be employed under any circum- 
stances where no steam roller is employed. 

14. Use chips, if possible, for binding newly laid 
stones together, and remember that road-sweepings, 
horse-droppings, sods of grass, and other rubbish, 
when used for this purpose, will ruin the best road 
ever constructed. 

15. Remember that water- worn or rounded stones 
should never be used upon steep gradients, or they 
will fail to bind together. 

16. Never allow dust or mud to lie on the surface 
of the road, for either of these will double the cost 
of maintenance. 

17. Recollect that dust becomes mud at the first 
shower, and that mud forms a wet blanket which will 
keep a road in a filthy condition for weeks at a time, 
instead of allowing it to dry in a few hours. 

18. See that all sweepings and scrapings are put 
into heaps and carted away immediately. 

19. Remember that the middle of the road should 



202 EOADS, PATHS AND BRIDGES 

always be a little higher than the sides, so that the 
rain may run into the side gutters at once. 

20. Never allow the water-tables, gutters and 
ditches to clog up, but keep them clear the whole year 
through. 

21. Always be upon your road in wet weather, 
and at once fill up with ''chips" any hollows or ruts 
where the rain may lie. 

22. "When the main coatings of stone have worn in, 
go over the whole road, and gather together all the 
loose stones, for loose stones are a source of danger 
and annoyance and should never be allowed to lie on 
any road. 

The Problem of the Automobile. — In the last 
few years the need of proper maintenance and 
possibly even a radical departure from some of 
the former methods of maintenance, especially 
on roads near large cities and the principal 
thoroughfares between cities, has been greatly 
emphasised by the advent of the automobile. 
We are confronted by a dust problem due to 
this new vehicle. Dust has always existed. 
The chemical, physical and mechanical agencies 
which produce the dust are in no way new. 
The automobile, when not equipped with chain 
tires, is not a dust producer in that it grinds up 
the road material; it takes the dust made by 



MAINTENANCE AND EEPAIR 203 

other agencies and disseminates it over tlie sur- 
rounding country. The broad-tired, swiftly 
moving automobile throws the dust from be- 
tween the stones and the strong, deflected wind 
current from the car blows the dust from the 
road surface into the air to be carried away by 
the wind to the detriment of the road, the travel- 
lers, nearby^ residents and bordering foliage. 

No one will seriously question the statement 
that the automobile has come to stay. Nor 
will it be wise, even though it should prove pos- 
sible, to limit the speed below that consistent 
with the proper safety of all concerned. The 
solution must be found, either by a change in the 
design of the cars so as to raise less dust, or by 
the highway engineer in the construction and 
maintenance of the roads in such a manner as 
to prevent the formation of the dust, or so as 
to retain it on the roadway when formed. 
Probably the ultimate solution will come from 
both sources. The other part of the solution 
rests with the highway engineer. Present in- 
dications point to two lines of procedure : pre- 
venting the formation of dust, and laying the 
dust when formed. 



204 KOADS, PATHS AND BEIDGES 

The prevention of the formation of dnst in- 
cludes the selection and use of materials which 
give very little dust, that is, those which bond 
very well and are very resistant to abrasion, 
and second, the use of binding materials other 
than rock dust in road construction. One of 
the evil effects of the automobile traffic at pres- 
ent is that the binder is all blown away, leaving 
the surface free to ravel, which in turn produces 
more dust to be blown away by the automobile. 
By using only the best materials, the dust nui- 
sance can be lessened to a considerable extent. 
Before a dust preventive of any kind is applied, 
however, the road must be in good condition, 
i.e., good repair. Dust preventives are simply 
another step in road maintenance, and in no way 
vitiate the need for a smooth, properly drained 
and properly repaired road surface. Having 
secured this, you are ready to take the advance 
step of applying some dust-layer or surface 
dressing to prevent its rapid formation; in 
other words, to lessen the wear on the road, for 
much dust usually means that the road surface 
is wearing rapidly. The dust on the road has 



MAINTENANCE AND REPAIR 205 

but two sources, viz., the foreign material 
brought on and ground up, such as horse drop- 
pings, etc., and the material abraded from the 
road surface. It is the latter which chiefly 
concerns the highway engineer. The rate at 
which it is formed is in a manner a measure of 
the wear of the road. 

The evil ^ effects however, go much further 
than the mere destruction of the road surface. 
Travel for health and pleasure is practically 
prohibited by the thick clouds which fog up 
from the disintegrating surface. This dust is 
carried by winds to the neighbouring fields and 
houses, to the extreme annoyance of the road- 
side dwellers and to the detriment of the crops 
and foliage along the way. In not a few places, 
the values of otherwise desirable properties 
have declined greatly because of the dust which, 
in extreme cases, prohibits the use of front 
porches and open doors or windows on the side 
toward the road. The question of public health 
is even a more vital one, however. Dust and 
disease are most intimately connected. Tyn- 
dall, the great scientist, once declared that the 



206 EOADS, PATHS AND BEIDGES 

ravages of war are small compared to the vic- 
tims claimed by that insidious, relentless arch 
enemy of mankind, dust. 

The proper use of the various substances 
which are used as binders or dust layers is dis- 
cussed in the chapter on Modern Eoad Prob- 
lems. 



CHAPTER X 
ROADSIDE TREATMENT 

Roadside treatment has received compara- 
tively little -attention in the United States, and 
yet proper attention to the roadside is not only 
essential to the beauty of the road and to the 
pleasure and comfort of the travellers, but also 
to the preservation of the road itself. 

Roadsides. — After a road is completed, rub- 
bish should be removed, and excavations and 
embankments, except such as are necessary to 
the road, should be smoothed over and sown 
with grass, and all unsightly brush and weeds 
removed. In short, wherever possible, the 
road should run between strips of smooth green 
sward, and suitable shade trees should be 
planted at intervals, so as to provide a pleasing 
appearance, shade for the traveller, and pro- 
tection to the road from drying out too rapidly, 
provided it is macadam or gravel. Clay and 
earth roads should be free of shade. Shade 

207 



208 EOADS, PATHS AND BEIDGES 

trees are an important factor in reducing the 
cost of maintenance of macadam roads, by rea- 
son of the fact that they prevent the road from 
drying out and becoming dusty. 

In the selection of shade trees care should 
be taken to secure only those which are suitable 
to local conditions. In all cases it is well to 
choose a tree that is hardy, grows rapidly, and 
has abundant foliage. A good plan is to plant 
trees with tops fifty feet apart, but alternating 
on each side of the road, so that there will be a 
tree every twenty-five feet. In some portions 
of Germany fruit trees are planted extensively 
along the roadside, and a considerable revenue 
is derived from the sale of fruit. In Saxony 
apple, pear and cherry trees are planted along 
the road from 90 to 120 feet apart, and plum 
trees about 25 feet apart. Upwards of $21,000 
a year has been obtained from the State roads 
of Saxony from this source, and still larger 
amounts from local roads. In India the Gov- 
ernment allows abutting property owners to 
take the produce of fruit trees in exchange for 
protecting and caring for the trees. The irre- 
pressible American boy is a factor which would 



EOADSIDE TEEATMENT 209 

have to be taken into consideration, if sncli a 
plan were ever contemplated in this country. 
With onr present inadequate system of mainte- 
nance which does not provide for daily patrol, 
it would probably be better to resort to forestry 
rather than to horticulture for guidance in road- 
side tree planting. 

Effect of .Trees on Roads, — The beneficial 
effect which is most generally apparent from 
the planting of trees is the prevention of dust 
in summer. On the other hand, it is contended 
that they prevent muddy roads from drying 
out. The presence of trees along the roadside 
is generally a partial preventive of damage to 
the road from hard, driving rains. A road 
shaded by trees is cooler by day and warmer 
by night during the summer, and is warmer 
both day and night in winter. By preventing 
the loss of heat by radiation, trees and tall 
hedges reduce the freezing of the road surface 
and, consequently, protect the road in a measure 
against the destructive action of frost. Shade 
also prevents the destructive effect due to rapid 
thawing of the road by strong sunshine in the 
spring. A great deal of damage is done to un- 



210 EOADS, PATHS AND BEIDGES 

shaded roads by traffic passing over them while 
the rapid thawing process is going on. 

Protection From Wind and Snow. — When de- 
termining upon the kind of roadside treatment 
to be adopted, consideration should be given to 
the protection of the road from snowdrifts in 
sections of country where the snowfall is heavy. 
A study of the relative positions of snowdrifts, 
the direction and velocity of winds, and the 
relative location of the road, would aid in de- 
termining what course to pursue ; for example, 
whether trees or hedges would be most advis- 
able, and if trees, what kind should be used, or 
if hedges, the kind, height, location, and method 
of planting. 

The protection of stone and gravel roads 
from wind is very important, as the continued 
prevalence of high winds tend to strip the road 
surface of the rock dust which is essential to 
the bond of the road. The injurious etfect 
from wind is most pronounced in summer when 
the roads are dry. Consequently, if the road- 
side is planted with trees or hedges, the foliage 
will be thickest in summer, so as to afford a 
screen which will materially lessen the force 



EOADSIDE TREATMENT 211 

of the wind before it reaches the road surface. 

The Kind of Tree to Select. — ^As previously 
stated, the important considerations in the se- 
lection of roadside trees are: first, adaptabil- 
ity to local conditions ; second, hardiness ; third, 
good foliage ; fourth, rapid growth. Wherever 
practicable, trees of local origin should be used. 

There are a great variety of conditions in 
the United States, and it would be impossi- 
ble to designate a list of trees which would 
be adaptable to all the road conditions which 
might exist in this country, unless it were de- 
sirable to limit the list to fruit or nut-bearing 
trees. If this were the case, the fruit-bearing 
trees which would be best adapted to road con- 
ditions would be the apple, and possibly the 
pear, in some localities. Apples would cover 
all that section of the eastern United States 
north of the Carolinas, and even south of this 
in the Appalachian region. West of the moun- 
tains the apple would serve as far south as the 
Gulf States, and west to the base of the Rocky 
Mountains, with perhaps the exception of the 
extreme northern part of Minnesota, the Dako- 
tas and Montana, where some other plants 



212 EOADS, PATHS AND BEIDGES 

would have to be substituted for tbe apple, un- 
less tbe crab were used. The nut-bearing trees 
which are adapted to this use in the eastern 
United States are hickory, walnut and butter- 
nut for the New England States, and along 
the Appalachian Mountains as far south as 
Georgia ; but the distribution of these nut trees 
would take a northern turn on the west side 
of the Alleghany Mountains, and they should 
not be used, perhaps, south of central Kentucky, 
and no further west than Colorado. The hick- 
ory will not thrive in northern Iowa, north- 
ern Wisconsin, Minnesota or the Bakotas. 
The black walnut, however, will grow well as 
far north as the southern part of Minnesota, 
over the eastern part of South Dakota, eastern 
Nebraska and Kansas. On the Pacific Coast 
the English walnut can be used as a substitute 
for the nut trees grown in the eastern part of 
the United States, and in the South Atlantic 
States and the Gulf States pecans may serve 
as a substitute for the other nut trees men- 
tioned. 

Ordinarily it is better to select some long- 
lived shade tree than to attempt to combine fruit 



EOADSIDE TEEATMENT 213 

production with shade. For the New England 
and Middle States the sugar maple is one of 
the most extensively used and one of the most 
desirable shade trees for this purpose. Elm is 
very desirable, but it does not produce as dense 
a canopy as the maples. If a more dense 
shade is desired than that produced by the 
sugar maple, the Norway maple may be sub- 
stituted. In localities from Washington, D. C, 
southward to the Carolinas, a variety of shade 
trees may be employed, such as silver maple, 
which is perhaps the least desirable of all ; the 
elm and red oak, similar to the varieties growing 
on Twelfth Street, Washington, D. C, along 
the side of the Smithsonian and Department 
of Agriculture grounds; the willow oak, a fine 
example of which is standing just across from 
the Henry Monument in the Smithsonian 
grounds, Washington, D. C. ; the Norway maple, 
which has long been considered as one of the 
finest shade trees for that locality; the pin oak, 
which is being so extensively used on the streets 
of Washington; and the sycamore, which has 
a natural distribution throughout the Middle 
States. After the confines of the Carolmas 



214 EOADS, PATHS AND BEIDGES 

have been reached, there is nothing which com- 
pares with the live oak. This should be 
planted to the exclusion of everything else 
throughout the southern part of the United 
States, because it is typical of the region and 
is one of the most beautiful trees grown in 
America. For California probably the pepper 
tree will supersede everything else as a road- 
side tree, while in Florida, the camphor tree 
might well be used as a substitute for the pep- 
per tree in California. In extreme southern 
Texas the native palm could be used very effect- 
ively for roadside decoration. Where this is 
not desirable, the hackberry, both native and 
Mexican varieties, may be used to good advan- 
tage. For the extreme Northwest, including 
the Dakotas and northern Minnesota, perhaps 
the best roadside tree would be the American 
elm or the green ash. 



CHAPTER XI 
MODERN ROAD PROBLEMS 

On roads wliicli are subjected to heavy auto- 
mobile traffic, the most important problem con- 
fronting highway engineers is the prevention 
of dust and the preservation of the road from 
the destructive action of automobiles moving 
at high rates of speed. The standard macadam 
road has been found inadequate to withstand 
this new form of traffic, especially when the 
automobile traffic is dense. 

As previously explained in this volume, the 
macadam road was designed for the purpose 
of withstanding the wear of iron-tired horse- 
vehicles. On a macadam road properly con- 
structed with suitable material, the amount of 
dust worn from the rock fragments is only 
sufficient to replace that which is carried away 
by wind and rain, so that the bond of the road 
is continuously preserved. The advent of the 
automobile has brought about new conditions. 

215 



216 EOADS, PATHS AND BKIDGES 

The driving wheels of motor cars moving at 
high rates of speed exert a powerful tractive 
force on the road surface, which displaces the 
materials composing the surface. The result 
is that the finer particles and dust are thrown 
into the air to be carried off the road by cross 
currents of air. The rubber tire of the auto- 
mobile does not wear any appreciable amount 
of dust from the rock fragments, and conse- 
quently, the loss of the rock dust is a permanent 
loss to the road. Under these conditions, the 
road soon ravels, making travel difficult and 
allowing water to make its way to the earth 
subgrade or foundation. 

In spite of the fact that the automobile is 
responsible for these and other unfortunate 
conditions, it must be realised that the automo- 
bile is one of the most useful inventions of the 
age, as it brings distant communities in closer 
touch, and places at the disposal of man a 
power for the transportation of himself and his 
products of infinitely greater possibilities than 
animal power. The automobile has come to 
stay, and we could no more legislate it out of 
existence than we could abolish the railroad and 



MODEEN EOAD PROBLEMS 217 

the locomotive. At the present time it is esti- 
mated that from 12,000 to 13,000 automobiles 
are manufactured every month, and the number 
is constantly increasing. Up to the present 
time most of the manufacturers have devoted 
their energies to supplying the demand for 
passenger ears, but the time will undoubtedly 
come when the automobile will be used quite 
generally for the transportation of farm prod- 
ucts to market over good roads. It is neces- 
sary, therefore, that attention be directed 
toward providing roadways suitable for this 
new form of traffic. 

Methods of Meeting Conditions, — ^All rem- 
edies which have been tried or suggested in this 
connection may be considered in two classes: 
first, those which deal with the construction of 
new roads, so as to minimise the formation of 
dust, and second, those which deal with the treat- 
ment of the surfaces of existing roads, to bring 
about the same results. In the construction of 
new roads various bituminous binders have been 
employed with crushed stone, and this type of 
road is known as the bituminous macadam. In 
the treatment of old roads various bituminous 



218 EOADS, PATHS AND BRIDGES 

and other binders have been applied to the sur- 
face, according to a number of different meth- 
ods. The materials which are applied to roads 
for the purpose of preventing the formation of 
dust may be considered in two classes: first, 
those that are applied in their original condi- 
tion, and second, those that are applied in emul- 
sion or solution in water. 

Mineral Oil. — This material has been quite 
generally used in the treatment of road sur- 
faces, with varying success. The oils that have 
given the most satisfactory results are those 
having an asphalt base. Asphalt forms an ex- 
cellent binder, while paraffin has practically no 
binding power, and would merely result in mak- 
ing the road greasy. The eastern oils contain 
almost a pure paraffin base. Some of the Ken- 
tucky oils, and most of those in Texas, have a 
mixed paraffin and asphalt base, while many of 
the California oils contain a high percentage 
of asphalt. The oil is applied either in the 
crude state or after distillation at refineries, 
where the lighter and more volatile parts are 
removed. An oil which has been refined in this 
way is known as a residual oil, is heavier and 



MODERN EOAD PROBLEMS 219 

thicker tlian in its original state, and possesses 
a larger percentage of the base. Consequently, 
it is, as a rule, better suited for road treatment. 
When the oil is not too heavy, it can be applied 
to the road surface with an ordinary sprinkling 
cart, but when it is too heavy for use in this 
way, it is uaual to heat it and apply it to the 
road by means of a sprayer, either with or with- 
out pressure. In the application of surface 
binders the best practice is to sweep the road 
clean, so that the binder may penetrate and be 
incorporated in the body of the road. After 
the material has been applied in this way, it is 
usual to place a thin covering of gravel, sand 
or rock screenings, and rock dust on the road. 
In California, oil has been applied to earth 
roads which have previously been ploughed up, 
and the materials thoroughly tamped and 
mixed by means of a tamping or sheep-foot 
roller. This method of construction has not 
proved successful in the East. 

Coal Tar, — Many engineers favour the use of 
coal tar for the prevention of dust and the 
preservation of roads, but one of the greatest 
difficulties is to obtain a universally good mate- 



220 EOADS, PATHS AND BRIDGES 

rial from different producers. Coal tar is a 
thick, black liquid, obtained as a by-product 
from the distillation of coal during the manu- 
facture of illuminating gas and coke. The base 
of coal tar gives its value as a road binder. 
This base, which is known as coal-tar pitch, 
corresponds to the asphalt base of oils. In the 
application of coal tar to roads, the dust should 
be removed and the tar applied in practically 
the same manner as oil. The refined tar is 
usually superior to the crude product, but is 
more expensive. The application of tar to 
a surface should be made only in dry, warm 
weather, and when the road surface is perfectly 
dry, as good results cannot be obtained other- 
wise. It would hold true, consequently, that 
the tar itself should not contain any water, 
as the road surface absorbs water more rapidly 
than other materials. It is almost always nec- 
essary to heat the tar before it can be applied 
to the road, and the method is usually to provide 
large iron kettles, equipped with portable fire 
boxes and mounted on wheels, or, where the tar 
is supplied in tank cars, the heating is done 
before the tar is removed from the tank. It is 



MODEEN ROAD PROBLEMS 221 

applied to the road either by means of a 
sprinkling device, or by hand sprinklers and 
spread with brooms. The tar should be al- 
lowed to dry for a few days before traffic is per- 
mitted on the road. The best practice is to 
spread a light course of sand or rock screenings 
over the surface after it has been treated with 
tar. 

Solutions and Emulsions. — Materials other 
than tars, asphalts and heavy oils, are generally 
included under the term ** palliatives." Pre- 
vious to the introduction of motor vehicles, 
water was the agency generally relied upon to 
keep the dust down on stone roads. Owing to 
the fact that water evaporates rapidly, a num- 
ber of chemical salts, having the property of 
absorbing and retaining moisture in the atmos- 
phere, have been used. 

Calcium Chloride. — Probably the best exam- 
ple of this form of dust preventive is known as 
calcium chloride, a by-product produced in the 
manufacture of soda. Calcium chloride has a 
great affinity for water, and absorbs and retains 
moisture from the atmosphere for a consider- 
able length of time. It is, however, only tempo- 



222 EOADS, PATHS AND BRIDGES 

rary in its effect, as compared with the heavier 
binders. It is prepared for application to the 
road by mixing with water, and is applied by 
means of the ordinary sprinkling cart. 

Waste Sulphite Liquor. — ^A waste product 
from the wood-pulp paper-mills has been re- 
cently used with some success, but as the base 
of this material is soluble in water, it can be 
classed only as a temporary binder. The best 
results have been obtained from this material by 
the application of a concentrated solution of 
about 1.13 specific gravity, at the rate of % gal- 
lon per square yard. Under favourable con- 
ditions, this treatment will keep the dust down 
for a whole season, and the material may, there- 
fore, be considered as a semi-permanent binder. 

Permanent Binders, — Coming now to the 
permanent binders, we may consider their use 
according to two general methods of construc- 
tion, known as the penetration or grouting 
method, and the mixing method. Among the 
permanent bituminous binders which we have 
so far employed are the heavier residual oils 
and tars of semi-solid or solid consistency, 
fluxed oil and tar pitches and solid native bitu- 



MODERN EOAD PROBLEMS 223 

mens, and fluid cut-back products, wMcli are 
capable of increasing in consistency after ap- 
plication, by volatilisation of the lighter con- 
stituents. 

When employing tbe penetration method, the 
best practice is to construct the road as follows : 
Upon the subgrade, prepared as for ordinary 
macadam work, a foundation course of No. 1 
crushed stone is placed to the desired depth 
and well rolled. Sufficient screenings are then 
applied to fill the surface voids, and care is taken 
that there is no excess of fine material which 
will prevent the wearing course from keying 
into the foundation course. The road is then 
rolled until absolutely firm, and more screenings 
are applied if necessary to take the place of 
those worked into the foundation. The wearing 
course of No. 2 crushed stone, clean and free 
from dust and screenings, is then applied to a 
finished depth of two or three inches and this 
course is lightly rolled. The hot bitumen is next 
poured or sprayed upon the road at the rate of 
from 1 to 11/2 gallons per square yard, after 
which a light coat of clean i^-iiich stone chips, 
free from dust, is applied and the road is well 



224 EOADS, PATHS AND BEIDGES 

rolled. A seal coat of bitumen is then painted 
upon tlie surface at the rate of from a third 
to half a gallon per square yard, after which 
screenings are applied and rolled in until the 
road is. smooth and firm. 

Such a method of construction should pro- 
duce a durable road on which dust formation is 
reduced to a minimum. The mixing method is, 
however, to be preferred because of the greater 
certainty of obtaining an absolutely uniform 
wearing surface in which each individual frag- 
ment is known to be covered with the binder. 

In general the mixing method is conducted 
as follows; Upon a foundation course of 
crushed stone, prepared as just described, a 
mixture of crushed stone and bitumen is laid 
to a finished depth of from two to three inches, 
and rolled with the addition of screenings. A 
paint coat of bitumen is then applied and the 
road is finished in the manner previously de- 
scribed. The mixture of stone and bitumen 
may be prepared either by manual labour or 
machinery, preferably by the latter. The min- 
eral aggregate may be graded in any approved 
manner. For country road work, the crusher 




THE AUTOMOBILE AND THE ROAD. 

1. Motoring on a road of bituminous macadam. 2. Tearing up the 
pike. 3. Hqw last, av.toraobile travel affects a macadamized surface. 



MODEEN EOAD PEOBLEMS 225 

run of stone from 2 inches or II/2 inches to dust 
may sometimes be satisfactorily used. In the 
experimental work of the Office of Public Eoads 
a mixture of 27 parts crusher run of from II/2 
inches to % inch with 10 parts crusher run of 
from % inch to dust has been found to produce 
a very dense, aggregate. Such an aggregate 
should be mixed with not less than six per cent, 
of bitumen, and neither the stone nor bitumen 
should be heated above 350° C. 

The application of rock asphalt in macadam- 
road construction may in a certain sense be 
considered as a combination of the penetration 
and mixing methods. This material, if contain- 
ing a good grade of bitumen, will serve as a 
permanent binder. It has been mixed by na- 
ture so that each individual fragment is thor- 
oughly coated with the binder. It is seldom 
suitable for use as a wearing surface of any 
considerable thickness, owing to the softness 
of the bitumen and to the fineness of the min- 
eral particles, which are not, as a rule, well 
graded. If forced into the wearing course of 
a newly constructed macadam road, to which no 
screenings have been applied, it may, as has 



226 EOADS, PATHS AND BEIDGES 

been demonstrated, prove to be a very service- 
able road material which prevents excessive 
dust formation by reducing wear and disinte- 
gration. 

In order that bituminous roads may be kept 
dustless it is necessary that they, in common 
with all other roads, be treated from time to 
time according to one of the first two methods 
mentioned earlier in this chapter, that is, they 
must either be scavenged, or their surfaces 
treated with temporary or semi-permanent 
binders. It will be found that the use of a good 
semi-permanent bituminous binder in compara- 
tively small amounts will not only lay the dust 
satisfactorily upon these roads, but that such 
treatment will appreciably lengthen the life of 
the road by revivifying the old binder originally 
used during construction. 

Portland cement is in some respects an almost 
ideal permanent road binder, especially when 
motor traffic only is encountered. When mixed 
in proper proportions with a suitable mineral 
aggregate it produces a hard rigid concrete, 
well designed to withstand the shearing strains 
exerted upon it by the driving wheels of auto- 



MODEEN EOAD PEOBLEMg 227 

mobiles, and practically unacted npon by tbe 
large pneumatic tires of such vehicles. Under 
steel-shod horse-drawn traffic it is, ' however, 
far from ideal, owing to its lack of resiliency 
and tendency to spall under impact and abra- 
sion. 

Investigations are now being conducted by the 
Office of Public Roads with a view to finding some 
way of overcoming these undesirable properties. 
While much experimental work will yet have to be 
done along this line, what has already been accom- 
pHshed would seem to indicate that certain fluid 
petroleum residuums may be used to advantage in 
wet cement concrete mixtures, both for the purpose 
of waterproofing the concrete and reducing its ten- 
dency to spall. It has been found that there is little 
difficulty in incorporatiug petroleum residues with 
such mixtures, providing they are sufficiently fluid to 
be handled when cold, and some of the oils seem to 
produce no loss in the strength of the concrete in 
which they are used. We hope in the near future to 
try out some of these mixtures in the construction of 
experimental roads where it will be possible to study 
the results produced under actual service conditions. 
Until this is done it is, of course, impossible to draw 
any definite conclusions in regard to the practical 
value of mineral oils as road preservatives and dust 
preventives in the construction of cement concrete 
pavements. 



228 EOADS, PATHS AND BKIDGES 

In conclusion a word may be said in regard 
to the value of an oil binder in eartb-road con- 
struction. While the experiments conducted by 
the Office along this line have been in no sense 
failures, it would seem that in the eastern part 
of the United States at least, the oiled earth 
road is not destined to prove a success. This 
is due both to the character of the oils which 
have to be used and to the rather severe climatic 
conditions encountered here. 



CHAPTEE XII 
PATHS 

There are many sections of the country where 
the roads are so poor as to render them prac- 
tically impassable for pedestrians, especially 
during the winter months. In other parts of the 
country where the roads are improved, the auto- 
mobile and wagon traffic is very frequently so 
heavy as to render the roads not only disagree- 
able but dangerous to travel on foot. School 
attendance in many rural districts is sometimes 
interfered with, and in some instances the 
schools have to be closed on account of bad roads 
for varying periods during the winter months. 

With the expenditure of a comparatively 
small amount of money, sidewalks or side paths 
could be built to accommodate pedestrians along 
the main roads where the conditions above de- 
scribed prevail. Side paths would facilitate 
school attendance and at the same time encour- 
age the healthful exercise of walking, a pastime 

229 



230 EOADS, PATHS AND BRIDGES 

that is too seldom indulged in by tlie average 
American. 

Paths should he located on the highest side of 
the road on the slope or shoulder just outside 
of the surface ditch. A strip of sod a few feet 
in width should be provided between the path 
and the road, as otherwise it will be found, if 
the path is on the same level as the road, that 
teamsters will drive their heavy wagons and 
horses over the line of the path and destroy it. 
The width of such paths need not be greater 
than 2 or 3 feet. 

A Sand-Clay Path, — For all ordinary pur- 
poses, a path built out of a mixture of sand and 
clay, or out of fine gravel, will serve every pur- 
pose. No foundation will usually be required, 
as the paths are not subject to heavy loads. If 
the ground over which the path is located is 
composed of clay or loam, and the surfacing is 
to be made with sand and clay, or sand and 
loam, the ground should be ploughed up slightly 
and then covered with a thin layer of sand. 
This sand should be mixed with loam or clay by 
means of a garden rake. The mixing should be 
done when the soil i^ comparatively damp^ and 




< 

Q 
(—1 
m 

W 

I— I 

K 

K 



PATHS 231 

the mixture should contain from 85 to 90 
per cent, of sand and from 10 to 15 per cent, 
of clay or loam. After the mixing process has 
been completed, a thin layer of sand should be 
applied to keep the clay or loam from becoming 
muddy or sticky in wet weather. The path 
should be slightly crowned so as to shed surface 
water, and small tile culverts should be placed 
under it at low places, so as to prevent washing. 
It will be unnecessary, as a general rule, to con- 
struct bridges and culverts for the paths, as the 
ordinary bridges and culverts of the roadway 
can be used by pedestrians. 

It will sometimes be found that the surface 
soil by the roadside contains about the right 
mixture of sand, gravel and clay to make a good 
path, and under such circumstances, all that is 
needed is to clear the right of way and remove 
weeds, rocks and other obstructions, and crown 
the surface. Where gravel is used, all large 
pebbles should be raked out and discarded or 
used for the foundation. There is nothing 
quite so disagreeable as to walk on a road where 
the surface is covered with large stones or peb- 
bles. 



232 EOADS, PATHS AND BRIDGES 

Stone Screenings, Cinders, etc, — Cinders are 
very frequently used for side paths, but as they 
are lighter and more friable than gravel, sand 
or crushed-stone screenings, they are more liable 
to wash, and consequently do not give as satis- 
factory results. Crushed sandstone, limestone 
chips and screenings, or other screenings, make 
good materials for paths, provided no piece is 
larger than % or % inch in diameter, and that 
the mixture contains enough fine material to 
cover the coarser screenings. As a general 
rule, 2 or 3 inches of any of the materials above 
mentioned will be sufficient. The materials 
may be laid directly on the sod or soil, as this 
insures better drainage than would be secured 
by digging a trench into which these materials 
are placed. 

When side paths are built in thickly settled 
regions, or in the neighbourhood of towns and 
villages, it is often found desirable to construct 
them out of more permanent materials than 
those referred to above. The materials ordi- 
narily used for this purpose are brick and con- 
crete. 

This advice applies in a general way to the 



PATHS 233 

construction of paths about one's house and 
grounds. 

Brich Walks, — In building brick paths, an 
excavation of 4 or 5 inches should be made to 
the desired width of 3 or 4 feet. The founda- 
tion may be composed of cinders, gravel or 
crushed stone, placed to a depth of from 2 to 3 
inches, and covered with a layer of sand to a 
depth of about 1 inch. A curb should then be 
laid on both sides of the walk, composed of 
bricks set on end with the upper ends flush with 
the surface of the ground. The bricks for the 
walk should be laid flat and not on edge. Every 
alternate brick should be laid lengthwise of the 
pavement, so as to avoid long cleavage lines or 
cracks. The bricks should then be tamped into 
position under a board, or, if possible, rolled 
with a light roller. The surface is then cov- 
ered with a thin layer of fine sand which is 
broomed into the cracks. 

Walks of Portland Cement, — The success of 
a cement sidewalk is largely dependent upon the 
provision of the following essential features of 
construction: 



234 EOADS, PATHS AND BEIDGES 

1. A firm, but porous foundation, to provide means 
for draining off rain water. 

2. A sufficiently thick base of well-made, strong 
concrete. 

3. A wearing coat of rich mortar, troweled to a 
smooth, dense surface. 

4. The division of the walk into blocks, with lines 
of weakness between them, so that all cracks due 
to settlement, shrinkage or frost, will be made to 
occur at the joints, and will thus not be notice- 
able. 

If proper drainage is not provided under a 
cement sidewalk, rainwater will accumulate, 
and in consequence the frost action will be 
severe in causing heaving in cold weather, and 
unequal settlement of the walk will occur when 
the ground is wet. Good drainage may be 
secured by laying a foundation of cinders, 
broken stone, gravel or coarse sand. Before 
laying the foundation, the ground is excavated 
to the proper depth and is well consolidated by 
ramming. The depth of the foundation course 
is dependent on the climate and the nature of 
the soil. In cold climates, or where the ground 
is soft, the foundation should be from 4 to 8 
inches deep, while, in the more temperate cli- 
mates^ where no frost occurs and the soil 



PATHS 235 

is sandy and not likely to become soft or water- 
soaked, no foundation is required. 

The foundation course should be thoroughly 
rammed to present a firm, unyielding surface, 
and if sand or cinders are used, they should be 
thoroughly wet when being compacted. 

The main body of the concrete walk is made 
of coarse concrete and is called the base. The 
usual proportions for the cement base are one 
part of cement, two or three parts of sand, and 
^Ye parts of broken stone or gravel. 

Nothing but good Portland cement should be 
used in sidewalk construction. Natural cements 
are unsuitable, since they will not stand the 
wear, while Puzzolan cements are likely to suf- 
fer deterioration through the action of wear 
and weather. 

The sand used in the concrete mixture should 
be clean and coarse; the stone should be hard 
and tough, and as free from dust as possible 
If gravel is used, it should be thoroughly 
screened and should be free from clay or other 
matter likely to interfere with the proper adhe- 
sion of the mortar. Gravel as it comes from 
the banks should not be mixed with the cement 



236 EOADS, PATHS AND BEIDGES 

to form concrete, but the sand should be 
screened out and recombined with the coarse 
particles in the desired proportion. The 
cement, sand and stone, or gravel, should be 
mixed with enough water to form a mixture of 
quaking or jelly-like consistency. Care should 
be taken to mix the materials thoroughly, so 
that each piece of stone will be coated with 
mortar. 

Forms should be provided along the sides of 
the walk to confine the concrete. These may be 
made of wooden strips 1% inches thick and of 
suitable depth, depending on the thickness of 
the concrete base. The strips should be nailed 
to wooden stakes, so that the tops are level with 
the finished surface of the walk. 

It is necessary to lay the concrete base in 
blocks with definite lines of separation, so that 
in the event of settlement, shrinkage or tem- 
perature changes, the irregular cracks which 
would otherwise form will be made to occur in 
straight, well-defined lines. The separation into 
blocks may be made by steel plates or strips 
about 1/4 inch thick, which are removed just be- 
fore the final finish and joint is made. Another 



PATHS 237 

metliod is to lay the blocks alternately and fill in 
between them. Good results can be obtained by 
cutting the concrete course to a width of % 
inch, and finishing the top coat into the cut to 
the depth of 1 or 2 inches, and cutting with a 
trowel through both to separate the blocks when 
finished. 

The size of the blocks depends upon the width 
of the walk. Blocks nearly square in shape 
have a better appearance than elongated blocks. 
The limit of size for a 4-inch walk is generally 
placed at 6 feet square. 

The mortar wearing-surface should be placed 
as soon as a few of the concrete blocks have been 
placed, and before they have set. This surface 
consists of a mixture of cement and sand, cement 
and finely crushed stone, or cement and a mix- 
ture of sand and finely crushed stone. Care 
should be taken to proportion the materials 
exactly, and thoroughly mix them so that the 
surface will be of uniform colour throughout. 
The size of crushed stone usually specified is 
that which will pass a ^-inch sieve. 

The consistency of the mortar to be used is 
such as is ordinarily employed by a mason in 



238 BOADS, PATHS AND BEIDGES 

laying brick. The mortar after being depos- 
ited on top of the concrete base is smoothed to 
the level of the side form by means of a straight 
edge guided by the top of the forms. The sur- 
face is then roughly floated with a plasterer's 
trowel, and soon after levelled with the straight 
edge. The final floating is not performed until 
the mortar has been in place from two to five 
hours, when it has partially set. For this ope- 
ration a wooden float is first used and then a 
metal float, or plasterer's trowel. It is some- 
times the custom to sprinkle a thin layer of 
** dryer," a dry mixture of 1: 1 mortar, which 
is trowelled over the surface. This is not desir- 
able, since it tends to make the walk glassy after 
floating. 

The surface should be grooved. The mason 
locates the joints between the blocks of concrete 
by marks previously placed on the wooden side 
forms. The exact location of the joints is 
found by running a small trowel down into the 
joints in the concrete. By the use of a steel 
straight-edge the mortar coat is cut through in 
order to form the individual blocks. The cor- 
ners of the cuts are rounded ofi by the use of 



PATHS 239 

a groover and edging trowel, wHch is a small 
float with one of its edges curved. A metal float 
is used over the entire surface to give it a final 
finish. To obtain a rough surface, a dotted or 
grooved roller may be employed. 

It is advisable to protect the walk from the 
hot sun for ^several days after its completion; 
otherwise the surface is likely to dry out too 
quickly, with the consequent formation of 
shrinkage cracks. 

The following table is compiled from the spec- 
ifications for cement sidewalk construction, as 
practised in some of the larger cities throughout 
the country. 



240 EOADS, PATHS AND BEIDGES 



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CHAPTEE XIII 
CULVERTS AND BRIDGES 

Bridge construction is a very teclinical and 
highly specialized field of engineering in which 
the layman is not likely to make great head- 
way. Nevertheless, there are many considera- 
tions regarding the construction and mainte- 
nance of culverts and small bridges which the 
layman can comprehend as well as the expert, 
and to these we desire especially to call the read- 
er ^s attention. 

By far the greater number of culverts and 
bridges on our public roads have a span of less 
than 50 feet. In the past these structures have, 
in general, been built of wood, but lumber so 
exposed is subject to rapid decay. Conse- 
quently, these structures require a great deal of 
repair and frequent renewals. The ever-in- 
creasing price of lumber is making the further 
use of wood for this class of structures more 
and more indefensible. The loads which our 

241 



242 EOADS, PATHS AND BEIDGES 

highway structures are called upon to sustain 
are also increasing. In many localities the 
movement of steam road-rollers and heavy trac- 
tion engines is seriously hampered because of 
weak bridges and culverts. Thus, considera- 
tions of both economy and safety demand the 
use of other materials than wood in the con- 
struction of our culverts and bridges. 

Road Bridges. — Eoad authorities should, in 
general, adopt some systematic plan of replac- 
ing all wooden structures as fast as they require 
renewal with permanent materials, such as con- 
crete, and they should take particular pains to 
make sure that all new structures have sufficient 
strength to carry a heavy road-roller. 

Wood should never be employed, except for very 
good reasons. When it is found necessary to use 
wood for the smaller culverts and bridges, certain 
practical, rather than theoretical, considerations 
should govern the builder. All beams and stringers 
should be carefully inspected and only those free 
from bad knots and other defects should be used. 
For flooring, select a lumber that is hard and tough. 
Planks that show a tendency to splinter should not be 
used. For 2- and 3-inch flooring, the spacing of the 
stringers should not exceed 2 feet in the clear. If 
the stringers are spaced as wide apart as the strength 



CULVERTS AND BRIDGES 243 

of the new plank permits, then in a short time when 
the plank is worn by traffic, failure will occur. 
Hence, to get the greatest possible amount of wear out 
of your flooring space the stringers closely. 

Culverts. — Three prime requirements are 
necessary in the design of road culverts, viz., 
ample waterway, strength and durability. All 
culverts and bridges should be designed and 
built strong enough to carry safely the heaviest 
load which is ever likely to be hauled over the 
road. For short spans, this is usually a heavy 
steam road-roller. Many of the existing 
culverts and bridges are far too light to carry 
the loads which they should legitimately be 
required to carry. This is especially true where 
traction engines are numerous. 

Durability is of the greatest economic im- 
portance. In many sections a large portion of 
the annual road levy is expended in repair and 
renewal of wooden culverts and minor bridges, 
and it is not unusual to find this practice de- 
fended on the grounds that the county or dis- 
trict cannot afford to build the higher-priced 
permanent culverts. This is simply a false 
sense of economy. True, the first cost of the 



244 EOADS, PATHS AND BEIDGES 

permanent strncture is greater, but tliere the 
outlay ends, while with wooden culverts, there 
is a large annual outlay for repair, as well as 
frequent renewals. Anyone interested in road 
improvements will find it most interesting to 
secure the following data for his own county 
or district: The number of culverts, cost of 
labour and material for repair and renewal each 
year, average life of wooden culvert, and the 
average life of wooden bridge floors. Then he 
could compute how long it would be before the 
actual present expenditure would pay for per- 
manent culverts. 

One of the frequent causes of the failure of 
culverts and bridges is due to inadequate water- 
way. Great care should be taken to provide a 
waterway ample to carry safely the largest 
storm-flow ever likely to occur. If the water- 
way is too small there is constant danger of a 
washout with interruption to traffic and high 
cost for repairs. On the other hand, if the 
waterway is made unnecessarily large, the cost 
of construction may be needlessly increased. 
Economical designs are those which provide 




COXCKETE CULYEKTS AND BRIDGES. 

1. (Top.) Bridge of concrete on the State highway at Bucklin, 
JSIass. 2. Tile culvert. 3. Arched culvert. 4. Culvert of the box type. 



CULVERTS AND BEIDGES 245 

adequately, but not extravagantly for all neces- 
sary requirements. 

It is inadvisable to carry storm water any 
considerable distance along the road. Water, 
especially where the volume is ever likely to be 
large and the velocity high, is a grave source 
of danger. Every effort should be made to turn 
water away from the road before it gathers 
in sufficient volume to be dangerous. To lead 
water long distances along the road, so as 
to require but few culverts, is the poorest kind 
of economy, as well as faulty engineering. It 
is courting trouble and inviting disaster. 
Pipe Culverts. — In many sections pipe culverts 




Cit099 Section 



End E4.Ev/mo^c 



Sketch Sxowinci 
foK Pipe, Cvuve R.TS. 



are proving very serviceable for sizes ranging 
from 12 to 24 inches in diameter. Because of 
the ease with which the smaller sizes of pipe 



246 EOADS, PATHS AND BEIDGES 

clog and so become unserviceable, it is in general 
inadvisable to nse for culverts sizes less than 
12 inches in diameter, even though the amount 
of water to be removed could be carried by a 
smaller pipe. The kinds of pipe most com- 
monly used are terra-cotta, concrete and 
iron. 

Terra-cotta, or tile culverts, should be laid 
very carefully with the earth well tamped 
around them and provided with masonry or con- 
crete end walls. There are three common 
causes for the failure of tile culverts : washouts, 
breakage by passing traffic, and breakage due 
to the expansive action of ice. These can, in 
general, be easily prevented. Washouts can be 
prevented by using a tile of proper size with 
careful placing, and the construction of suitable 
end walls — a point of great importance. End 
walls should 'be carried well below the pipe to a 
good foundation, and provision should be made 
against possible undermining by erosion. 

If the soil is fine sand, or very friable, the 
joints should be laid in cement. When the soil 
is tough clay, hard pan or similar formation, 
this is not necessary, but in every case the earth 



CULVEKTS AND BEIDGES 247 

should be carefully tamped beneath and around 
the tile. 

To prevent breakage by passing traffic, it is 
in general only necessary to place the tile at a 
greater depth below the surface than has been 
customary. The most frequent causes of break- 
age is on earth roads, where the wheels of heavily 
loaded wagons cut deep ruts, sometimes actually 
striking the pipe, when, of course, failure takes 
place. The remedy is obvious. On earth roads, 
place the tile at such depth that wheels will not 
cut to or near it. To prevent the softening of 
the earth, provide good surface drainage. A 
load or two of gravel spread over the road at 
this point will also be of much assistance. In 
general, never place a tile culvert nearer than 
18 inches to the surface on an earth road. 

In cold climates, and especially in the prairie 
regions, tile culverts are often broken by the 
expansive action of the ice in winter. A tile 
culvert should never be placed where there is 
danger of the drainage being obstructed in 
such manner as to allow water or slush to 
accumulate in the pipe and then freeze. When 
the pipe is as much as two-thirds full of water 



248 EOADS, PATHS AND BEIDGES 



or slush, hard freezing will invariably burst it. 
For this reason, tile culverts must be used with 
caution in all cold countries, and especially in 
the flat prairie regions, where the natural drain- 
age is poor. 

Iron-Pipe Culverts. — With regard to iron- 
pipe culverts, the same care should be taken 




CoiMCKE-TE Culvert 

Steeu l-BEflrts Incased 

In Coimcrete. 



in laying and placing the end walls as with 
tile culverts. Improvements in the manu- 
facture of iron have made this material more 
generally available for use in culvert construe- 



CULVEETS AND BRIDGES 249 

tion. A special quality of iron, very low in 
carbon, is found to resist corrosion so well as to 
make its use advisable in many cases. The old 
style of cast-iron pipes is too heavy ever to come 
into general use. Corrugated iron pipe, bow- 
ever, wben made from material of tbe proper 
quality, possesses strength together with dura- 
bility and lightness. Corrugated iron pipe can 
be laid with somewhat less covering than tile 
pipe, and will successfully resist the expansive 
action of ice. It can, therefore, be used in 
places where it would be foUy to place tile. 

Concrete-Pipe Culverts. — Concrete, both plain 
and reinforced, is used to some extent in the 
manufacture of culvert pipes. When care- 
fully made of proper materials, they are very 
serviceable. In general, it may be said that for 
the use of plain concrete culvert pipe, the same 
considerations govern as for the tile pipes, while 
the reinforced concrete culverts may be used 
wherever under other considerations the cor- 
rugated iron pipe could be used. 

End Walls, — What the foundation is to a 
house the end walls are to a culvert. Without 
suitable end walls, a culvert is without protec- 



250 EOADS, PATHS AND BRIDGES 

tion and is placed in danger at every severe 
storm. Where the fill is high, wing walls may 
be used to hold it back, but for most pipe culverts 
they are not needed. In friable soils, and when- 
ever the velocity of the water is high, the space 
at the outlet end of the pipe should be paved to 
prevent erosion and danger of undermining the 
end walls. The end walls should be carried 
down to soil sufficiently firm to prevent any set- 
tlement. 

The materials for end walls may be brick, 
stone or concrete. If bricks are used, they 
should be hard burned and laid in cement mor- 
tar. Concrete is in general the best material for 
use in the construction of wing and end walls. 
The concrete should be about a 1:2% :5 mixture 
The length of end wall should be about D + 3 H, 
where D equals diameter of pipe and H equals 
height of fill above bottom of pipe. 

Concrete Culverts, — In general the best ma- 
terial for use in the construction of culverts and 
the smaller bridges is reinforced concrete. The 
first cost of a reinforced concrete structure is 
naturally higher than that for a wooden one, 
but if properly built in the first place, the struc- 



CULVEETS AND BEIDGES 251 

ture will be permanent and the items of repair 
and renewals will be eliminated. Safety, whicb 
is of tlie greatest importance, will also be 
secured from the outset. 

There are four general types of concrete 
culverts and bridges, i. e., box, T-beam, I-beam 





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and arch. The box culvert may be used up 
to spans not to exceed 10 or 15 feet. The floor 
is a plain slab of reinforced concrete, while the 
abutments, wing walls and bottom may be built 



252 EOADS, PATHS AND BEIDGES 

of either plain or reinforced concrete. Wliere 
it is not necessary to protect the foundation 
from erosion, or increase the heaving of the 
soil, the concrete bottom may be omitted or, 
in some places, a cobblestone paving may be 
economically substituted. 

For spans above 10 or 15 feet, the T-beam 
type is quite generally used. Instead of in- 
creasing the thickness of the slab, the additional 
strength is secured by building longitudinal 
beams beneath the floor slab to carry the load. 
The beams and floor slab are built simultane- 
ously, and steel reinforcement is placed near the 
bottom of the beam and also near the bottom of 
the floor slab. In the I-beam culvert steel I- 
beams are placed beneath the floor slab to carry 
the weight. The concrete covering of the beams 
is added simply to protect the steel from corro- 
sion. This type of culvert is very readily con- 
structed with but little skilled labour, and has 
in many sections proved very economical. 

The arch culverts may be built of either plain 
or reinforced concrete, and are adapted for 
almost any length of span, provided the foun- 
dation is good and ample headroom may be had. 



CULVEETS AND BEIDGES 253 

Arch culverts and bridges must be very care- 
fully designed and require close supervision 
during construction. Wbere the headroom is 
small, or the foundation poor, the arch type will, 
in general, not be found economical. Under 
no consideration, however, should this type of 
structure be attempted unless competent engi- 
neering assistance is available, both for the de- 
sign and supervision of the construction. 

Forms, — Much ingenuity and skill is required 
to secure economical forms which also provide 
for the necessary strength and tightness. The 
appearance of the concrete depends much upon 
how well the forms are made. Every crack 
between the boards and every joint that is 
poorly made or any other imperfection in the 
forms is filled with the wet concrete and leaves 
its impression upon the finished structure. For 
the boards next to the concrete, it is well to use 
green, or only partially seasoned, lumber, which 
is not so likely to warp and swell out of shape. 
For the parapets and other surfaces which will 
be exposed to view, it is advisable to use planed 
lumber. Working a spade or shovel along the 
boards will crowd back the larger particles, 



254 EOADS, PATHS AND BEIDGES 

allowing the finer mortar to flow close to tlie 
boards, thus forming a smoother surface. The 
forms should be coated with soft soap or crude 
petroleum in order to prevent the concrete from 
adhering to them. On the parapets, wing walls, 
etc., the forms may be removed as soon as the 
concrete will safely hold its shape, and these 
exposed surfaces may be rubbed smooth with a 
wooden or brick block. 

The main part of the forms should not be 
removed until the concrete has attained suffi- 
cient strength to carry safely the stresses to 
which it will be subjected. The time required 
will vary with the brand of cement used and the 
temperature. Concrete sets much more rap- 
idly in warm than in cold weather. Ordinarily, 
the forms may be removed in from one to three 
weeks after the placing of the concrete. 

Mixing and Placing Concrete, — In large quan- 
tities concrete is most economically mixed by 
machine. In smaller quantities, however, it is 
better to do the mixing by hand labour. 

The following considerations should always 
be kept in mind. The materials should be so 
proportioned as to secure the densest mixture 



CULVERTS AND BRIDGES 255 

possible. The materials should then be so thor 
oughly mixed that each particle will be coated 
with a thin coat of mortar. In general work, 
for those parts requiring great strength, the 
proportion of 1:2:4, that is, by measure, one 
part cement, two parts sand, and four parts 
broken stone or gravel, gives satisfactory re- 
sults. For hand-mixing a platform 10 or 12 
feet square will be found advantageous. The 
sand is first placed on the platform and the 
cement added. The sand and cement are then 
turned with shovels until the mixture has a uni- 
form colour. The stone or gravel is then placed 
on top, water is added with a bucket or hose, 
and the turning is continued until the whole is 
thoroughly and uniformly mixed. 

Metal wheelbarrows are commonly used to 
convey material from the mixing platform to 
the forms. As the concrete is placed in the 
forms, it should be well tamped. The consist- 
ency of the concrete should be about such that, 
after thorough tamping, water should flush to 
the surface, and the concrete should have the 
appearance of quaking like a mass of jelly. 

It is neither possible nor advisable in one 



256 EOADS, PATHS AND BEIDGES 

chapter to go into the details of bridge design. 
These belong to the highly specialized and tech- 
nical field of bridge engineering. We have en- 
deavoured only to cover those subjects for the 
proper understanding of which a high degree 
of specialized knowledge is not necessary. 
When it comes to structures of any considerable 
size, we can not be too emphatic in urging that 
competent engineering supervision be secured, 
both for the design and construction. Every 
question of both safety and economy in bridge 
construction has competent engineering super- 
vision as a prerequisite. We know of no other 
way in which both safety and economy can be 
assured. 



AUTHORITIES CONSULTED 

In the preparation of this book the following au- 
thors were freely consulted. 

AiTKEN, Thomas — Road Making and Maintenance, 
London, 1907. 

Baker, Ira 0. — A Treatise on Roads and Pavements, 
New York, 1905. 

Bergier, Nicholas. — History of Great Highways of 
the Roman Empire, Brussels, 1728. 

Bloodgood, S. DeWitt — A Treatise on Roads, Al- 
bany, N. Y., 1838. 

Bruce, P. A. — Economic History of Virginia in the 
Seventeenth Century, Vol. I. 

Byrne, Austin T. — Highway Construction, New 
York, 1907. 

CoANE, John Montgomery — Australasian Roads, Mel- 
bourne, 1908. 

Elliott, Charles G. — Engineering for Land Drain- 
age, New York, 1910. 

Frost, Harwood — The Art of Road Making, New 
York, 1910. 

Gallatin, Albert. — Roads and Canals, Report to U. 
S. Senate, April 6, 1808. 

Gillespie, W. M. — A Manual of Road Making, New 
York & Chicago, 1871. 

Gillette Halbert P. — The Economics of Road Con- 
struction, New York, 1906. 

257 



258 EOADS, PATHS AND BBIDGES 

Green WELL, Allan and Elsden, J. V. — Roads, Lon- 
don, 1901. 

Herschel, Clemens — The Science of Road Making, 
New York, 1894. 

HooLEY, E. PuRNELL — Management of Highways, 
London. 

Hubbard, Prevost — Dust Preventives and Road 
Binders, New York, 1910. 

HuLBURT, Archer Butler — Historic Highways of 
America, 16 Vols., Cleveland, 0., 1902. 

Jeffreys, Rees — Dust Problem Statistics, London, 
1909. 

Jenks, Jeremiah W. — Road Legislation for the Amer- 
ican State, Baltimore, Md., 1889. 

Johnson, J. B. — Engineering Contracts and Specifi- 
cations, New York, 1902. 

JuDSON, William Pierson — Road Preservation and 
Dust Prevention, New York, 1908. 

Latham, Frank — The Construction of Roads, Lon- 
don, 1903. 

LovEGROVE, E. J. — Attrition Tests of Road-Making 
Stones, London, 1906. 

Low, Henry and Clark, D. K. — The Construction of 
Roads and Streets, London, 1901. 

Preliminary Report of Inland Waterways Commis- 
sion, U. S. Senate Document 325 60th Congress, 
1st. Session. 

Richardson, Clifford — The Modern Asphalt Pave- 
ment, New York, 1908. 

RiNGWALT, J. L. — Development of Transportation 



AUTHORITIES CONSULTED 259 

Systems in the United States, Philadelphia, Pa., 

1888. 
Ryves, Reginald — The King's Highway, London, 

1908. 
Searight, Thomas B. — The Old Pike, Uniontown, 

Pa., 1894. 
Shaler, N. S. — ^American Highways, New York, 1896. 
Spalding, Frederick Putnam — A Text Book on 

Roads and Pavements, New York, 1908. 
TiLLSON, G. W. — Street Pavements and Paving Mate- 
rials, New York, 1908. 
Tucker, James Irv^in — Contracts in Engineering, 

New York, 1910. 

Annates Fonts et Chaussees, Paris. 
Engineering and Contracting, Chicago. 
Engineering News, New York. 
Engineering Record, New York. 
Good Roads, New York. 
Surveyor, London. 
Zeitschrift fur Transportwesen 
und Strassenhau, Berlin. 

Bulletins of U. S. Office of Public Roads. 
Bulletins of U. S. Department of Agriculture. 
Bulletins of U. S. Geological Survey. 



THE END 



INDEX 



Appian Way, 10. 

Asphalt, ancient use of, 5, 17. 

See BITUMEN. 

Automobiles, effect on roads, 

202, 215. 
Authorities consulted, list of, 

256. 

Binders, permanent, 222. 

Binding qualities of various 
stones, 169. 

Bitumen, application of as a 
binder, 224. 

Bond-issues for road-improve- 
ment advisable, 52. 

Bridges, general considera- 
tions, 241. 

Britain, Roman roads in, 12. 

Broken-stone roads. See ma- 
cadam. 

Buckshot, or gumbo soil, 114. 

Calcium chloride as a binder, 

221. 
Carthage, roads of, 8. 
Causeway, Egyptian, built by 

Cheops, 4. 
Cement walks, how made, 233. 
Chariots of the ancients, 4. 
Chert gravel, qualities of, 129. 
Clays, properties of, 113, 116. 
Clay road. See sand and 

CLAY ROAD. 

Concrete walks, how built, 
233. 



Convict labour on highways, 

46. 
Crushers for stone, 147. 
Culverts, construction and 

types of, 243-256; proper 

placing of, 94. 
Cuts and fills, directions for, 

98-101, 151. 



Disc harrow and its use, 103. 

Ditches, form and arrange- 
ment of 90, 105. 

Drag, the split-log, form and 
use of, 183, 189. 

Drainage of roads, importance 
of, 87; methods of insuring, 
88-98, 152-155. 

Dust, controlling the evil of, 
204, 217, 226. 

Dynamite, use of in road-mak- 
ing, 142. 

Earth road, the, care of, 182; 

construction of, 79-109. 
Economics of good vs. poor 

roads, 54-61. 
England, early road-maldng 

in, 24; Turnpike Acts, 27. 
Epaminondas of Thebes, 8. 

Flaminian Way, 10. 
France, origin of road system 
in, 20, 22. 



261 



262 



INDEX 



Grade of a road defined, 82; 

method of determining, 85. 
Gravel, qualities of, 125. 
Gravel road, the, 124-133; 

care of, 187, 191. 
Gumbo or buckshot soil, 114. 

Highways, ancient imperial, 4, 
5, 6-18. 

Labor-supply affected by bad 

roads, 59. 
Land, increase in value due to 

good roads, 57. 
Legislation as to public roads, 

22, 27, 38. 
Loam, properties of on roads, 

114. 
Location of a road, advice as 

to, 64, 80; importance of, 

62, 80; value of surveys 

for, 65. 

McAdam, J. L., biography of, 
28. 

Macadam or broken-stone 
road, the, 134-102; care of, 
194, 198; cost of, 161; 
courses of stone in, 157; 
drainage of, 152-155; first 
in the United States, 31 ; 
foundation for, 155; select- 
ing materials for, 163-176. 

Machinery and implements. 

See ROAD-MAKING MACHIN- 
ERY. 

Maintenance of roads, 177- 



236 



American neglect of. 



180; French system, 50, 
180; importance of syste- 
matic attention, 49. 

Mediseval ruin of the high- 
ways, 18, 21. 

Mudholes, treatment of, 93. 

National Turnpike, the, 33. 



New England Path, the, 31. 

Office of Public Roads, origin 
of the, 35 ; work of the, 36. 
Oil for surfacing roads, 218. 

Paths, construction of, 229- 
240. 

Pavements in old times, 7, 25. 

Personal service on roads a 
bad policy, 21, 44. 

Peruvian road construction, 
17. 

Plans and specifications, rules 
for making, 68, 71-78. 

Plough, the, and its use, 104. 

Policy of road administration 
recommended, 40. 

Population affected by condi- 
tion of local roads, 59. 

Post-service, ancient, 6; early 
posts in the United States, 
31. 

Public roads: public owner- 
ship necessary, 42 ; econom- 
ics of, 54 ; financing, 57 ; 
more than local institutions, 
48. 

Quarrying for road-material, 
139-143. 

Repair of public roads, 177- 
206. 

Roads in ancient times, 6-18. 

Road-grader, the 103, 107, 
148. 

Road Improvement Associa- 
tion, rules of, 200. 

Road machine, the, 107-109. 

Road-making, revival of in Eu- 
rope, 20. 

Road-making machinery, 101, 
143, 147. 

Road roller, use of the, 147, 
158. 



INDEX 



263 



Road sprinlder, tlie, 147. 

Roadside, treatment of the, 
207-214. 

Roadway, preparatory clear- 
ing of the, 98. 

Rocks classified as road ma- 
terial, 165; specific gravity 
and weight of, 149; suitable 
for macadam, 163; tests for, 
172. 

Rock asphalt as a binder, 225. 

Roman roads, construction of, 
10-14; maintenance of, 14. 

Sand and clay, directions for 

mixing, 115, 117. 
Sand-clay road, the, 111-123; 

care of, 185. 
Sandy roads, treatment of, 

121. 
School attendance affected by 

condition of the roads, 60. 
Scrapers and their use, 102, 

106. 
Shade trees, selection of, 208, 

211. 
Snow, protection against, 210. 
Spreader, the, 148. 
Stone crushing, advice as to, 

143-146. 



Stone, first use in bridges, 5. 
Subdrainage of roads, methods 

of, 94, 96. 
Sulphite liquor as a binder, 

222. 
Surveys for new or improved 

roads, 65-78. 



Tar for surfacing roads, 219. 
Telearch, Greek, office of, 7. 
Telford, T., biography of, 29. 
Tile drains, how laid, 154. 
Tolls, bad policy of, 22, 27, 33, 

43; first collected, 6. 
Trails, the forerunners of 

roads, 3. 
Tresaguet, biography and 

work of, 23. 
Turnpikes in the United 

States, 30, 33. 



Walks of cement or concrete, 

233. 
Weeds, grass, etc., harmful, 

109. 
Width proper for roads, 98. 
Wind, protection against, 210. 



JUL 20 1912 



LIBRARY OF CONGRESS 



028 145 851 6 



